So, there's an inaccuracy in your recount of this debacle. Out of the 5 artworks of Epic 7, that the artist did, 2 were sfw (I included the fanart submission) and all were deleted from the artist's twitter timeline. In addition, based off of people that are infuriated about this term of events, it seems that he also uninstalled the game as well. However, this conclusion was based on hearsay.
Also, it seems like people believe that the ones who are angry are blowing this out of proportion, or believe Smilegate is in the right. I disagree. Upon reading the rules, it never states that NSFW artists are banned, just that NSFW entries aren't allowed, or specifically, entries must be PG13. WASP has broken no rules layed by Smilegate, yet was still disqualified.
IF they still wanted to preserve their image of the game, at the very least, WASP, should still be compensated for Smilegate's fault of not establishing the rule of artists having to be absolutely clean of NSFW.
Next point: vote manipulation. There is nothing in the rules that states that you cannot advertise yourself on different platforms. In addition, I do not believe vote manipulation is an appropriate reason. Vote manipulation implies WASP used bots in order to win the competition, which I have not seen any inclinations of. Beyond very literal interpretations of the words, there is the argument that WASP used his followers that don't play Epic 7 to help vote for his submission. I did not participate in the fanart competition, so I have no knowledge on how the votes were legitimized. But, can't votes be tied to the ID of your account? If so, then it'd be a good thing, since his followers would have downloaded the game to vote for him. If there was no system in place, then WASP still should have been compensated for Smilegate's mistake.
Now, this gets into my conspiracy theory... but due to all the negativity in the community, I believe Smilegate relented to community backlash and arbitrarily banned WASP for the sake of saving face. Not because of the NSFW artworks on other platforms, but rather, in order to get clout from their community since boobs > gay furry is the majority. Really unfair due to the sheer amount of effort in that artwork, honestly. Have you seen it?! It's awe-striking! 7 characters all in different layers and poses and emotes, a detailed melon dish, on top of all the amazing nuances in the lighting! The only thing of issue would be how muscular Jecht is, compared to the actual model.