Lilmod Ulelamed – I can tell you that I was specifically told that the fact that someone is not Shomer Shabbos does not cause wine they touch to become Assur. This psak was given in a Kiruv context, where we were having a non-observant family over for a Shabbos meal. I asked my Rav if I had to get wine that was Mevushal, and he said that in nowadays, we do not treat a non-frum Jew as a non-Jew for the purposes of Yayin Nesech – unless the Jew is following another religion.
Of course, you should ask your own Rav, as there clearly are different views on this.
an Israeli Yid