grammar - が and けど at end of a sentence

I know that when in a sentence-final position が and けど can be used as softeners or to convey hedging, but in some situations understanding them as such doesn't feel right. Although my brain instinctively wants to interpret them as "though", I can't think of any reason that would be correct. Here's an example from a story, spoken from the point of view of the narrator:

彼は唯一の生き残り。無論、生き残ったのには理由があるからなのだが。

Would translating it as something like this be wrong: "He is the sole survivor. Though of course, it's because there's a reason he survived."

I can't understand how だが's usage here would indicate hedging or softening, but "though" doesn't make sense either. Could someone help me get this?