For me, giving a blow job is a much more up close and personal sensory experience than PIV sex. So yes, for me it could be more intimate.
Not to be too clinical, but the times where I've felt giving a blow job was more intimate than PIV sex would have involved the following:
1) the guy is encouraging/complimentary and enthusiastic, but not too enthusiastic!
2) he's well groomed, showered recently, etc
3) he uses his hands and body to show he's enjoying himself, again not too enthusiastically
4) possibly it's been a long time since we've been together, or it's the first time I'm going down on him - missed or new smells and tastes are especially intimate when they're good (see #2)
On the flip side of that, if he has his way with my mouth and throat to the point where I'm gagging, choking, and worrying I might suffocate, that too would be more intimate than PIV sex.