He is specifically a wholesale dealer, so that it was a lot, he should let them know. That it's a one-way ticket to Hell, no. Anyone dumb enough to buy Sin wholesale... well, buyer beware!

SO: An Infiltrator who got a skill proof for it and did not claim the skill would be unaffected post-Jaunt.

An Infiltrator who Takes The Skill will have lasting effects, but not as extreme. It is meant to be a negative skill the way that Eldritch stuff in Harrogate is/was.