[seiji]

isn't a computer limitation it is a physical one.

Assumes facts not in evidence. That could easily be a firmware (on-gate) vs. software (DHD) argument.

Carter said it is "impossible" due to physics

Potentially unreliable narrator.

also established that with enough raw power (e.g. blackhole, ancient device, etc) it could be kept open longer

Yup, cited above.

built their own DHD which presumably would have different computer limitations

firmware vs. software

when all DHDs in the universe died except theirs due to the malware

you're not doing devops unless you have one button that can destroy your entire infrastructure