While being up to date when it comes to voting for witnesses is an important thing, I wouldn't say that it's always a problem when people are voting for someone who is offline.
@arhag for instance, has my vote since the beginning and I'm well aware that he has his witness disabled for now and I've already talked with him about that.
So, TL;DR:
- it might be ok to vote for disabled witness
- it's not ok to vote for witnesses blindly
Why not encourage active witnesses with your precious vote, until @arhag comes back (if he plans to)?