Twitter bans go on keywords and mass reporting, if you block jews/antifa/fbi/journos (but I repeat myself) and don't use no-no words you can generally get away with things. They also do collective bannings though which I'm not sure how he escaped, I've had accounts banned in ban waves where they just wiped thousands of accounts that have connections with each other a few times. Those ban waves are random though so it's possible he just got lucky whenever they came around. Maybe they were using his account as a kind of beacon to locate other accounts they want to ban, the ban waves being seemingly random suggests their strategy was to continually wipe large chunks of dissidents without wiping all of them in order that they can more easily track them by using the same 'key' accounts that they use to find connections from. If they wiped us all at once they'd have to start from square one in tracking dissidents.

Twitter is different to youtube and reddit and such, much harder to censor.