Answering directly to your question: no, they're not decentralized. Answering with more context: no, they're not and they're doing exactly what some topics ago we were discussing or what Stratum v2 is really trying to resolve. If the first block they mined, they used filters¹ to prevent certain types of transactions THEY don't like. I'll assume their hashraters didn't like also.

In fact, it's funny how these things works, Luke Dash in the past put biblical verses without asking anyone and without pay. And now they want to filter with their OP_RETURN version. Come on, man.