Indeed, they are. Well, Bitcoin.com belongs to Roger so Roger = Jihan = Bitmain.
Not just that. Bitcoin.com announced that they will use 2x chain as a main chain, they will literally ignore the legacy chain.
You shouldn't listen to nor take anything that Roger Ver says seriously. He's a spoiled manchild. He recently said that Bitcoin Cash is the true Bitcoin, then change his statement to 2x a few days after. His statements are worthless, nor is he or this band of suits able to define Bitcoin.
Bixin also supports Segwit2x from the beginning.
That does not necessarily have to imply that they are a Bitmain proxy (and I sure hope that they are not). There's still time for them to pull out of the agreement.