I would agree and I think it points to this being a deliberate act. One strsin escaping may be an accident. Two strains centered in different parts of the world and resulting in far different outcomes...accident...I don’t think so.
The European (==Eastern US) virus is definitely a successful mutation of the virus that was in China. It outcompeted the Chinese version by its better ability to reproduce (thus to infect too).
The Western US virus is the original virus, thus the problems in California and St. of Washington -- places where the virus showed up first -- are minor comparing to the East Coast.
But: we don't even know who had the virus first: California or China or some other places. Estimates show that the weaker version of the virus existed as early as September 2019... but it also can be a mutation of something that existed in humans *somewhere* even earlier.