For most of the Christian world, including the Early Church, 2 Maccabees is inspired Scripture so there is some confidence in that. Even if it isn't it still reflects the tradition of at least some Jews living close to the time of Jesus. If one does accept it as inspired, like other Scripture we still would have to make sure we are interpreting it right. The fact that the writer mentions previous accounts of this is some evidence, though it would be nice if we had access to that or other corroborating evidence.
Given the passage of time and the unsettled nature of that era, I think that other possibilities should be considered.
Oh, I think so too, as long as it wasn't pure speculation without supporting biblical, literary or archaeological support.
This also goes for theories about the physical Ark's possible recovery. As I noted in my previous post, "Of course other scenarios are possible, but I don't know of any documentary or other evidence for them. According the account given in 2 Maccabees (which states that the account there was taken from other records, probably now lost to us), Jeremiah, when he hid the Ark and the other Temple implements in the cave on Mt. Nebo, set very specific conditions for when they would be found again." There is a possible spiritual fulfilment of the disposition of the Ark of the Covenants, but I'd rather not get into that on this thread.
Would you leave the Ark on Mt. Nebo and trust to its security even though that was its declared resting place? Or would you secretly move the Ark to somewhere new, letting the account in Maccabees stand as a way to divert attention.
Call this speculation, but it does offer an explanation for why the Ark has not been found.