I don't think it is that bad.  I mean, it is terrible to wait until the cock is in and about to cum before asking for it to be taken out and cum elsewhere, but at the same time a poz load can be quite terrifying too.  Hard to get over the hump at times I would guess.  I had trouble letting a guy cum in me that undetectable for quite a while before I finally let him and have now had 10 or so of his loads in me (although it has been quite some time since the last one).  I finally let it decide upon the flip of a coin to do it, but I had already promised to let him if the coin toss was in his favor, which actually didn't happen until about the third or fourth time I flipped it.  Now, I have actually had two hvl poz cocks in my hole but both freaked out on me some and neither could cum in me and I had already decided they could when ready.   It is still a very tough decision and I don't think it should be taken lightly at all.