I understand you (and by the way, three cheers to you for not replying), but you see what that implies: in certain companies, for certain jobs, you are assumed to be available 24/7. Well, unless I was a futures trader, or something like that, pulling down a five figure bonus at the end of the year (or six?), and obviously in a job where markets are worldwide and shifting all the time, there is no way I would accept that. No way.
Certain doctors are, I believe, on call like that. That also, you can understand.
Otherwise, I think it's downright rude. Your ex-boss is clearly someone who doesn't have a life. Sad, in a way.