Past + として used in a sentence instead present [duplicate]

Question

彼がうちの会社に来た理由を聞いたとして俺はどうする
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The character saw a friend at his company and now he's wondering why did he join? Did he do it for him?

I do know するとして is used for suppositions, but I don't understand why he used the past here.

Answer 1

Seems like the friend joined the company because of the speaker and this reason, if known, would be problematic to him.

It's similar to とすると and としたら. Literally としても without the も particle. Keep in mind that the て form gives the idea that the clause that follows is somehow a consequence of the first one, but not so strongly as としたら does. I translated it as "if" regardless, but you get the idea.

[CLAUSE NON-PAST] + とする -> To assume [CLAUSE NON-PAST] (meaning we don't know whether [CLAUSE NON-PAST] is true, but we regard it as true).

[CLAUSE PAST] + とする -> To make a hypothetical assumption about [CLAUSE PAST] (meaning we do know that [CLAUSE PAST] didn't happen, but we presume it did)

I found this particularly confusing because [CLAUSE NON-PAST / PAST] とする is often translated as "If I were to [CLAUSE].." and many [CASE]とする can be written in both past and non-past.

彼がうちの会社に来た理由を聞いたとして俺はどうする
If I assume someone had heard the reason he joined our company, what should I do? / Assuming I were to ask him the reason...