I don´t consider it a flaw but a compelling incentive for commercial content creators (companies, advertizers, etc.) to buy SP. Imagine this post would be the corporate blog from Coca-Cola. At this stage they would only need to buy 100k worth of SP to have guaranteed exposure on trending. I personally would consider this a much healthier way to get advertizers on board as opposed to third-party ad placements that are ruining the web experience of millions.
There should be a second trending tab that exludes comment rewards from the ranking though. The possibility to opt-out from seeing such self-voted posts would ensure, that advertizers really try to appeal with their content.