It would be much like if Steph's visit to Myrellion had caused her to become a venom addict, or Tarkus had given her a cock from one of those lapinara that pass eggs out their dick: you would be pushing the fetish on people who didn't agree they wanted in on it first.
It's not *quite* the same as that. Worth bearing in mind Steph gets all sorts of shit pushed onto her involuntarily anyway, including a tail cock. She's a way for people into involuntary TF-ing to enjoy that kind of thing without it impinging on the rest of the audience.
The NT sequence got canned because it was a forcible, permanent chemical lobotomy followed by an on-screen rape. It matters that the person doing the raping is a mostly human guy acting like a psychopath, as opposed to a savage species Irson foolishly riles. Even then it might have scraped within TiTS' very loose understanding of what is acceptable, given at that point Steph was a cartoon character to whom it was accepted this sort of thing happened to. However then you got to meet Steph, and it turned out she wasn't particularly happy about it or any aspect of her recent career (or rather, she palpably *wanted* to be unhappy about it but no longer had the capacity to be), at which point most of the audience went "eesh". As I said before, the whole episode is a case study in making sure your boner doesn't overwhelm your better judgment, particularly if you're writing stuff you're going to have to justify and pick through the rubble later. Leave it to the bad ends, in other words.