Just think about it for a sec.
If you could travel through a black hole and end up in an alternate universe AND a black hole formed in the center of your ship you have two options if one were to travel through it.
Move forward - This would transport your aft section through the event horizon and to "elsewhere", but it would end up destroyed because your forward section didn't make the same trip. It's sitting where you were originally without it's ass end.
Reverse - This would transport your forward section through the event horizon and to "elsewhere" but it would end up destroyed because your aft section didn't make the same trip. It's sitting where you were originally without it's front end.
Both courses would destroy both halves of the ship in both universes.
Chuck 'er in reverse Trev. Oops.
Actually, going through that black hole (wormhole) seems like trying to put your finger through the hole in a doughnut you have already eaten.
Starfleet has exceptions to the PD, especially when a planet has a valuable mineral or drug ("Friday's Child", "Code of Honor")
Hmmm. Good point. Perhaps the involvement of the Klingons in the first one is some excuse but I'm not sure about "Code of Honor". It does seem strange they would stand so heavily on "principle" sometimes but not others? Well, unless we are both missing something (I haven't rewatched the ep)?
* Apparently some people have Googled: "doughnut hole recipe"!