Well, here's the thing DH seems to be struggling with. This young woman has every right to make these decisions, and it sounds like she's being very sensible, not leaping into doing a degree, any degree, but aiming to figure out what she actually wants to do first.
Yes, he could kick her out, if you backed him up on that, but hopefully he wouldn't be that stupid. She has a job already, she doesn't sound like she's planning on lying around all day eating bon bons. (In which case I'd be giving my kid short shrift! She will need to up her hours, perhaps?
She could be asked to pay board, to make it clear there's a difference between being at school, and now she's expected to support herself.
Maybe tell your husband he himself is behaving like a petulant child, tossing his toys, because he's not getting his own way, and to wind his bloody neck in? Not speaking isn't going to help matters. Finding out your daughter's plans, intentions, hopes and fears, and supporting her on her life path, might, however.