re: Is Biden wanting to debate in June to avoid them switching him at convention?

One key thing is that the debates are probably not going to be broadcast on all stations like in the past. CNN is hosting the Summer one and the fall one will be hosted by ABC.

So there may not be widespread broadcast of the debates, unless those 2 networks are going allow a pool feed to be rebroadcast on the other networks. Clips of the debate will be of course shared on social media platforms everywhere.

Also, the CNN one will be in studio with no audience.