I think the problem is that the article is written in a such way, that it can be interpreted that you must remove deck floors to reload torpedoes into the tube (from the rack).
I think it's reasonable to assume you need to do this to load all torpedoes into their storage area on sub.
I also found this video:
I know it's a different sub, but the torpedo is the same and at least the ramming process seems similar to what shipkiller1 has said.
In this video the process takes 1.5 minutes but you can clearly see how much has been cut out.
If you add all the necessary wiring then suddenly 15 minutes doesn't seem that much.
It also just appeared to me, that it seems like the upper tubes can be loaded only with the torpedoes from the upper rails. Otherwise it would increase load times even more.
Too bad we can't implement realistic reloads (reloading 1 port and 1 starboard torpedo at a time) without the help from the devs. But we can modify the reload times to somehow simulate the same effect (like setting reload times to 7.5 minutes for a single tube).
I think I'm gonna play with those things for my mod
