I disagree on the first point. Well, not disagree so much as I think you're arguing at something that doesn't exist. If you remove authorial intent and textual context, yeah you wind up reducing the characters to their archetypes, and that sucks. However, most fanon shippers don't do that. They see the authorial intent, they see the textual context...and then they say 'I like the idea of these other two characters together'. That's something completely different from disregarding the intent and context. It's something based off of their own reading of the text, with their interpretation of the subtext, so you can't very well tell them that their interpretation of it's wrong based on your interpretation of it.

The second point, though, I agree with very strongly. I hate when fandom morons forget that it doesn't really affect their fandom activities what is and isn't canon, and how shipping is not a fucking contest. I doubly hate the character bashing that comes out of that, and triply so as it almost invariably focuses on the female characters.

I just don't get why some people feel it will somehow invalidate their preferences if they aren't canon.