I hear what you are saying and suggest that you set an example for yourself. You can take him aside privately and let him know the "way of the land' or simply make a class announcement that everybody is expected to work together on the tasks that Sensei sets before them. If that person is not willing to do so, he is simply asked to remove himself from class so that there will be no discord and that you will be more than willing to discuss your action directly with him after the class has ended and in private.
The other issue to consider is that the best wishes and expectations of others do not always exist in reality. The teacher is responsible for the WHOLE CLASS. No discord among the whole class can also mean removing a divisive element from the mix. Frankly speaking, I think that the Dojo Cho needs to step to the proverbial plate on this one and set the standard, because there is visible discord in the dojo. Just because it is not being directly confronted does not mean that it is not plainly evident for all to see.
It has become apparent to other students unfortunately. He's been taken aside in the past. He at this point i think is doing stuff that is warranting that he should excuse himself from the mat.
I when I see a beginner not getting the training they need to be getting, I'll specifically tell that beginner to trade partners, forcing my problem student to train with a more senior student. I always make sure he partners with some one who won't accept him correcting them. In which he just gives that poor senior student crap ukemi, which pisses that senior student off. I'll also try to change to line techniques in which he's not allowed to teach anyone, which he typically just sits out. And then I have to say to him quietly to cut it out when he tries to encourage others students to also sit it out... like I'm giving them inferior instruction. I've been doing this about 15 years longer than this guy, so it is frustrating to see him trying to make they younger students not trust the way in which I'm leading them. It so far has just lead to a very strained personal relationship with this guy. Because i'm constantly after class having to say "Hey man, what was up with that?! Not cool!"