I have a D2 open face helmet and thought it would be nice if I could take this on a skiing holiday instead of hiring some smelly helmet countless people have worn.

Does anyone know if this will be acceptable?

Why not? Some of the latest ski helmets are designed to be skate/jump park helmets in summer.
Snow and rock

might be a bit hot but no reason why you couldn't. would probably whip the peak off it if you do.

ooo there's a problem

Pisspots and suchlike are designed without ear warmers so would need to wear a buff covering the ears. Troy Lee has solid ears though so should be OK.

I wouldnt wear a ski helmet to MTB but the other way about should be fine.

+

=

NO!!

Oh come on! You can't compare a D2 to Eddie the Eagle…
I wear my D2 open-face snowboarding all the time. Not only am I super cool but my head stays nice and toasty warm too! Totally acceptable (and if it wasn't who cares?)

P.S. Peak stays on too!