The books add no clarity since Ashford is very different there, in fact one of the huge improvements over the books (there aren't a lot!) is Ashford. In the book he's a vain blowhard who shows up just to be a threat, and then is neutralized. He always read like a cardboard character in the book to me (he's only in one). In the series they really fleshed him out as ostensibly a "bad guy" at the start but ends up becoming a close compatriot to Drummer (who herself is a complete fabrication of the series stitched together from several characters).
I
I agree the Marcos attack has a couple of question marks. For one thing, the Tynan (Ashford's ship) isn't huge with a large crew. My guess is that was his entire crew, hoping to take them by surprise. It was a trap, Marco's crew was hiding. I agree, it's a bit of a brow-raiser, but Ashford was always bombastic and there's nothing to really suggest that the attack on Marcos was really a suicide mission. I wouldn't assume it's a given that these ships have huge crews. But yeah, I understand why it might bug you a bit.