GPL – I don’t really care what flavor you use but won’t anyone think about the users?
The risk of keeping a public list of all ‘naughty WordPress plugins’ does not outweigh the benefits of having such a list.
A short trip into grep, plugins and how it’s totally okay to use the word ‘porn’ in a plugin!
When you say ‘this is broken, fix it!’ that’s probably not what’s going to happen. User expectations, process comprehension, and a little understand goes a long way.
The tl;dr for this post is that I don’t like Tumblr, and find it a clunky, poorly supported psudeo-blog and you should use something else.