The difficulty is proving they moved over deliberately and not for some other reason. If they didn't leave their lane, excuses such as "I sneezed", "I saw a pothole/animal" or even "I was trying to get a view around the vehicle in front", are all going to go a long way when all they have done is inconvenience a motorcyclist, especially when they may not be expecting an overtake in heavy traffic when nothing else has been overtaking. Of course, it might be different if they knock you off, but even then, and even with a helmet cam, it is going to be difficult to prove they were in the wrong unless they moved out of their lane.
It is not a case of whether someone did something wrong, it is being able to prove it. Regardless of whether they were in the wrong or not, it doesn't help you if you are lying in the road injured or worse with a broken motorcycle.
There are a number of times I have thought someone moved over to block me when in fact they were simply trying to get a view past the traffic and when they realise I am there move out of the way to let me through. Equally there are times when it is clear, to me, that someone has deliberately moved in the way. It used to piss me off, now I just get a greater satisfaction when I do get through, because in reality they have cost me no more than 5 or 10 seconds, and they are the ones that have elevated their blood pressure, not me.