Always fascinating to read about the almost-successes of any field but scientifically, it's all the more fun. Astronomy is a complete mystery to me so seeing a man make such a grand discovery only for it to be deemed 'wrong' is amusing. The sentimentalist in me hopes that if that the planet does exist it will be named after him, as a small Easter Egg of sorts. I can't judge his input on any grand scale, having little familiarity with the field, but I'd assume a bright mind shouldn't be forgotten just because of a mistake, particularly one that he wouldn't have made if he had access to modern tools. Plenty of greats were wrong about things, being wrong is halfway to being right after all.
That was a great article, loved how it describes that his techniques were ahead of the ability to use them reliably with scientific tools of the time.