This is like a denominational argument. Two groups both claim to be, for example, the only ‘real’ Evangelicals.
The truth is, one group does not get to dictate to the other. The Whiteness group can pout all day that they are the ONLY Alt-righters. It doesn’t make it true. Neither does your contention that some Freepers post at The_Donald mean that the site itself isn’t Alt-right. If an atheist attends a church service, it doesn’t mean the congregation ceases to be Christian.
I spend ~an hour a day on The_Donald. They fully and enthusiastically embrace the designation, Alt-right. It’s who they are. For some reason, you can’t accept that. You want to dictate that only a piddly little identity group can rightfully claim that title.
You don’t have that right or that power. If an energized, dynamic, growing and dedicated group says they are Alt-righters, you’ll simply have to broaden your definition. For example, I don’t deny that your micro-subreddit is Alt-right. Like Paul Watson, I acknowledge the obvious: that there are two types of Alt-righters. One focuses on whiteness and the other doesn’t. You may not like the fact that the group unfocused on whiteness calls itself the Alt-right, but that personal reaction changes nothing.
You have a very narrow, rigid POV. I can’t change it. But there’s something you can’t change, either. It’s the fact that the vast majority of high-energy, passionate and almost uniquely motivated group at The_Donald call themselves the Alt-right. When Paul Watson posted his tweet about the two Alt-rights, The_Donald users couldn’t feature it or upvote it fast enough. He spoke for them. And you don’t.
Here is another good synopsis.