> With that said, not being a native speaker, if I had to turn "sequestration" > into a verb, I would say "sequestrate" too and it would sound right to me...
There are a few other words that don't follow the pattern. "filtrate" is the fluid that has been filtered, but I don't think "to filtrate" is a valid word. And "orientation" is the act or result of orienting, not "orientating".