I know of an irreligious Israeli who influenced a woman who was brought up in a charadei family to be irreligious. He told her that she should be “free” like an Israeli. I realize that his status as a tinok shenishba is questionable as he was brought up in Israel and he has seen religious Jews. Although, the influence of secular media and lack of religious education do a play a factor. They got married, live on a secular kibbutz, and, needless to say, they don’t keep Shabbat, kashrut, or Taharat Hamishpacha. I should mention that the woman was an at-risk and troubled adult before she married him and very vulnerable to his influence. The purpose of the question is not to judge this individual. Obviously, there are many other variables. I just want to get a better understanding of where we draw line between a tinok shenishba who we don’t blame for his ignorance and a a tinok shenishba who influences another for his own benefit to become irreligious. It seems that even an irreligious person innately knows that it is blatantly wrong to influence a religious person to go off the derech.
You are correct in what you have written that even an irreligious person innately knows that it is blatantly wrong to influence a religious person to go off the derch. There is a big dispute regarding trying to define who is considered a tinok shenishba, Many Poskim seem to hold that now days a tinuk shenishba is not common.
Rambam Mamrim 3:3, Teshuvas Haream (R.E.Mizrachi) 57, Mabit 1:37, Radvaz 1:796 quoted by the Shach Y:D 124:1, Teshuvas Ginas Verodim Klal 2:31, Teshuvas Marikash 33, teshuvas Beer Mayim Chaim 41, Igros Moshe E:H 1,82-1, O:CH 5 28:22, Oz Nidberu 9:55, Minchas Shlomo 2 4-10, Shvet Halevi 2: 172 & 9:198, Chut Shoni end of Shabbos.