Yes, they are as they should be in protecting their property. However, it is important to understand Disney does not go after everyone. They target those who are trying to make a profit without a license/permission or are using their property in a way that went against Walt Disney's express wishes.
Trust me, I understand it is a risk that Disney might issue a C&D. However, I think the likelihood of this happening are not even slim to none and chances are greater the C&D will come from NCSoft before anyone like Disney. Trying to infer that a Disney suit is somehow imminent because someone made a Hulk character is fear mongering.
Again, I have no issue with the rules that Homecoming has set forth. I will be even more clear that if someone is naming their character Superman or Batman or Captain America, then yes they should get it changed.