2 minutes to who? Basso? Scarponi? Purito? Pozzovivo? Fränk? Nieve? He's at least equal to all of those, and better than most. Kreuziger? Contrary to the myth, he's not a good time-trialist on this kind of distance and course. Hesjedal? Well he might be better on paper, but not by much, not enough for it to be a factor. Tiralongo? Yeah right. Gadret? Haha.
The only people he could conceivably lose some serious time to are Pinotti, Vande Velde, Bruseghin, De Gendt, even Intxausti, and none of them are particularly likely to be actual contenders (Beñat could surprise, but I don't see him above 6th or so in the final GC, and he's not *that* good of a time-trialist either).
If Rujano climbs at last year's level, there's no way he'll lose the Giro in the ITT. The question for me is whether he's at that level. Personally I'd be surprised if there was more than a 1 minute or 1 minute and a half gap between the vast majority of contenders. Well Nieve could easily lose 2 or 3 minutes, I'll give you that.