No one is proposing a literal "suicide door". But it makes sense to have it openable after surfacing, at least for emergencies.

"Surfacing" unassisted would mean floating with the top of the submarine at water level. You still won't be able to open the door.

That's possible. Then at least some form of ventilation usable after surfacing should have been included if you're locking people in.

Every thruhull is a potential source of death at 5000+ psi.

The bigger problem seems like underinvestment in "getting found" technology.

There is 96 hours of oxygen onboard, and even without any supplement, 5 people would survive in a space that large for at least half a day with no fresh air