At least then Twitter would have a pretty clear incentive to combat your bot as it and its ilk could have a substantial effect on their revenue. No doubt this will happen. You could already be doing this on youtube to flag a competitor's content as copyright infringement.

Well, Google has figured out how to make it really hard to make a link farm that gets your web page to the top of the listings.

Very similar problem. I would expect that they would keep track of who is doing the flagging and whether their flagging is consistent with other flaggers, and various other tests for "naturalness" and lack of bias and so on. Then weight things appropriately.