One thing worth clarifying: Not all drivers will work well ported, but all drivers will work sealed. Yes, this is no longer "as intended" by the designer, but that doesn’t mean this isn’t a better match with a sub.
You are playing with the bass response here. You raise the -3 dB and make a gentler slope. You are not making the "ideal" sealed speaker. There are differences.
Generally speaking, an "ideal" sealed speaker uses a smaller volume of air vs the ideal ported speaker, so if you just plug a ported speaker, without reducing the volume you end up with a speaker that is normally orveramped... BUT!! ... in this case you are doing so specifically for a subwoofer, which means overdamped is fine.