First of all, even Dengists agree to there being a lot of revisionism in the Soviet Union for the majority of its existence, so we can hardly throw the "anti-revisionist" title out just like that. Second, there were and are a lot of Marxists who believed in some approximation of what Mao was doing even towards the end of his life, who see Deng being reinstated from the exile Mao put him in, and seizing power by banishing all the Maoists as being essentially a coup. This was followed by a massive reversal of many different policies, seizing collectively owned land from the people and selling it off, re-establishing the bourgeoisie, and ostensibly abandoning class struggle which you can hopefully forgive them for perceiving as being not very Marxist.

Even if you end up supporting what he did, most SWCC-ers do not deny that he was a right-deviationist, which is a subcategory of revisionism, they just also accuse Mao of being a revisionist to the left in equal measure. How they can both be "70% good" when they were so fundamentally opposed to each other is, uh, difficult math to swing.

For the record, I do think China remains a historically progressive force and should be completely supported over the US, so I guess I haven't explained what would be the literal meaning of "Anti-China marxism", but a lot of people use that phrase to ask about Maoists rather than Trots (people who totally oppose China, usually), so I chose that interpretation.