[caminante]

IMHO, he was defensive in the way you suggest. He got ~25% upfront.

But let's assume he got 100% upfront.

More importantly, he didn't protect scope or contract change requests. That was the time to contract. It sounds like collecting 100% would've been leaving money on the table for value delivered.

I like your label for "fix your mess" guys, but I know/use a few who definitely bill and get paid much later (especially lawyers). Sucks for OP that he contracted with a CN firm with credit risk.