I think consensus is that it's a very variable issue but its potential lives in every single spider. If you're not cool with it, I'd advise not to get a snake with the spider gene. I didn't do my homework and while I enjoy my bee and wouldn't give him back at this point, I would have bought a non-neurologically impaired snake if I could go back in time. He functions perfectly fine by the way.
I think the other consensus is that if the guy is claiming the snake doesn't wobble AT ALL, then it means A) he's playing with words by telling you that it doesn't wobble... what he means is he hasn't observed it express the wobble or B) he's straight up lying to you.
If it's something that gives you a little bit of a negative visceral reaction like it does to me, I'd advise against it. There are plenty of other morphs out there that don't have issues.
You might want to watch your words with possibly accusing someone of lying.