Yes, I understand that Thayer's Greek Lexicon has that possible meaning based on the two verses he referenced. And yes, he's not around anymore to discuss ("argue") his evidence both for/against that meaning in Matt 10:28 and/or James 4:12. It's not my goal to "argue" his meaning but rather to discuss the reasoning he used and the implications thereof. Which can be evaluated, even though he's not around to debate it further. There are several points of reason against his definition 1e given for the word "destroy" as used in Matt 10:28 and James 4:12. Here are some that I can think of. I just simply thought them through and thought it might be worth sharing with others in a post (since I documented it anyway). It's not necessary for you to consider these points but if you so desire and if you desire to provide any counter-arguments or point out errors in my thinking process here, I'd appreciate it.
1. Thayer's Greek Lexicon was published in 1890 without the aid of all the Greek language scholarship developed since then using the numerous Greek manuscripts found since then (some older than his and in better condition to the ones he had available). Plus the advent of computer technologies to accurately catalogue each and every usage and cognate of a word (no small or error proof job without a computer's help). Plus the well established 1st Century Jewish based hermeneutical principles (what did the writings mean to a 1st Century Jew, versus an 19th Century Englishman) have become recognized as utterly important since the late 1800's.
But my point here is that other, more modern, Greek Lexicons disagree with his 1e as a possible semantic range of meaning for the word itself:
Dodson dictionary
ἀπόλλυμι (Verb)
(a) I kill, destroy, (b) I lose, mid: I am perishing (the
resultant death being viewed as certain).
From: Public Domain
Greek-English lexicon by John Jeffrey Dodson (2010)
Or From Logos' dictionary:
ἀπόλλυμι
destroy, destroyed
perish, perished, perishes
lose, loses, losing
lost
die, dying
put to death
passing away
2. Also with respect to thinking his possible meaning (1e) through, the idea that the word itself has a figurative definition is obviously wrong and contrived. No word has a "figurative or metaphorical definition" (except the words figurative and metaphorical, I suppose). On the contrary, it's usage within sentences and contexts establishes the word is being used figuratively or metaphorically. The context and usage determines whether (or not) any word (not just this one) is used in a figurative or metaphorical way, not the definition itself. Take the Greek word λόγος, Logos (word), for example. One of it's definitions is NOT logos = Jesus. But it's figurative usage sure is at numerous times (especially in John's writings). Greek to English Dictionaries (Lexicons) are supposed to define (by translation) Greek words, not interpret passages for us. And for "logos", they do just that. But Thayer stepped beyond the bounds of a definition into the area of interpretation by publishing 1e obviously.
3. Point 2 is why I pointed out that in James 4:12 it doesn't even mention Hell, yet Thayer includes "Hell" within his definition 1e for the word apolesai and references James 4:12 for his justification. That's ridiculous and obviously his personal interpretation of a post judgment place called Hell derived from other passages and other words. I happen to agree with him that after the GWTJ the lost are sent to Hell for "apolesai". But I don't get Hell from the meaning from that particular verse or from "apolesai"'s definition. The definition of apolesai is not a synonym for Hell (literally or figuratively) yet he has literally included Hell into his possible English definition of apolesai for these two verses. That's just plain wrong. Obviously so.
4. Also, do you think God is merely able to metaphorically (figuratively, so-to-speak) destroy souls in Hell but will not actually exercise His ability to metaphorically (figuratively) destroy souls in Hell? It seems one or the other options to reconcile Matt 10:28 with ECT is possible but not both of these at the same time.
It seems Thayer takes the figurative supposition of destroy into Matt 10:28 and/or James 4:12 but not the idle threat approach. Yet you mentioned that Matt 10:28 just says God's able to do that (literally destroy souls, as the text says) but will not ever follow through with that ability. Which is technically correct. That's what it says. He's able to. But the point is that Auburn is figuratively able to "destroy" LSU. A figurative ability to "destroy" anyone is nothing special. We all can do that.
So which is your view, 1 or 2 (you've mentioned both)?
1) A figurative definition of apolesai?
or
2) an idle threat of a literal definition of apolesai?
or
3) both 1) and 2) i.e. an idle threat of a figurative definition?
or
4) Jesus' literal command to literally fear the literal God who is literally able to literally destroy literal souls in the literal future in a literal place called Hell (Gehenna)?
I see no reason to answer anything other than 4). But then again, I don't believe in the Eternal torment of lost people's bodies or their souls in Gehenna. Why? Because they don't have the gift of Eternal Life or posses immortality naturally
within either their bodies or their souls or a combination of both. Both are derived from God and sustained by God as all things created are.