@sissyphos For someone unaccustomed to deepthroating, it probably will. But some experienced guys can do it.
The safest way is to not breathe while he cums (it's a process of ~15 seconds, after all), all you do is constantly swallow (that's what I do).
Some guys can breathe (at least inhale) even when their partner cums by probably blocking the accumulating cum with their throat muscles or maybe by timing the breath just right (I can't do that---yet). Usually they breathe with their nose but I found this guy who does it with his mouth even with an unloading lengthy cock stuffed down (at 1:02 on the following video). For each spurt (about nine in total), you can hear a gulp. If your partner is lengthy enough, each gulp will literally milk their cock's shooting head by grabbing and pushing it within. It's the best experience ever.
VIDEO ON PORNHUB
https://www.pornhub.com/view_video.php?viewkey=ph60a0402809285&t=55