Welcome to FR.
Yes, it is legal. Indeed, if anything, your complaints seem to arise from the fact that they have taken steps that a good lawyer would recommend.
Since it appears that the bloggers have not followed Biblical mandates, church discipline would seem to be not only appropriate, but necessary.
It does sound like the bloggers would be happier in a connectional church rather than one that is congregational in structure.
What do you mean “connectional church”? I haven’t heard that term before.