Well, I wouldn't necessarily call him a patriot or regime supporter or whatever (not a vocal one anyways), but he indeed did like to occasionally throw some stones towards non-systemic opposition, color revolutions supporters, or other likely-minded people. One example would be what he wrote 12.12.2015 (exactly 4 years prior to current incident) at http://sysoev.ru/ about Berezovskiy's alleged financial support of orange and tulip revolutions of 2004-5.

So in that respect it isn't that impressive that he stayed in Russia even when (mostly non-state) news became more and more disturbing. Probably even less so if you assume a line of reasoning that nobody would bother with relatively small foreign company built around open-source product, a company that's already sold to larger foreign company (conveniently forgetting about the price that F5 paid for that company).

(edit: s/american-registered/foreign/: Nginx Inc. was registered in British Virgin Islands)