Crossfire and Assault

[upintheattic]

I say no because it does not meet the requirements of the rule where the two fires must go through two non-adjacent hexsides. BTW, if the target is still in assault hex, is it not legal for someone outside the hex to fire into it?

Agreed on the former point; the answer is no. On the latter, see rule 12.53; a unit outside an assault hex can fire into the assault hex with AT fire if only the enemy has vehicles in the assault hex.