This I am afraid is not true either, though. I know many dual-use companies who discovered an RFP (not just on SAM), late -- i.e. with a proposal deathmarch -- and got through.
That said, aggregators like bonfire etc. can get you pretty far if that’s your strategy!
So because the amounts are large (compared to commercial, in terms of when a customer first buys from a small company), those cases really make a huge difference.