I don’t have much hope for them being good faith

You said you believe he’s actually read Marx. If he’s read Marx, but just has a different opinion on it than you do, how is that not a good faith position? He’s not just trolling or speaking to something he has no knowledge of. Clearly it is possible to read Marx and not 100% agree with everything he had to say.

NJR was doing a sectarianism by publishing this article too

Sectarianism isn’t just disagreeing with someone. It’s more than offering a critique of someone’s ideas. It’s bitter, it’s vitriolic, it leads to an unwillingness to work with the person one is criticizing. “NJR is a lib fancy lad” is far, far closer to sectarianism than “I have some disagreements with Marx and how leftists use Marx, and I’m going to explain those disagreements in detail.”

instead of dedicating more of CA space and his personal efforts to anti-capitalism

Like this? Or like this? He publishes anti-capitalist stuff on CA multiple times every week.