I was just wondering why is it then when wine becomes Mevushal, we say it is ok for contact for contact with non-jews/non-religious people?
The Gemara (Avodah Zarah 30) writes that the prohibition does not apply to mevushal wine.
The reason for this is that in the past, wine that was mevushal (cooked or boiled) was of lesser quality that uncooked wine (the Meiri makes this point). This deterioration made the wine unusual (the Rosh highlights this point), so that the enactment of Stam Yeinam did not apply. See also Ritva, who writes that mevushal wine was uncommon, and therefore not subject to the enactment.
For this reason, some authorities (such as Rav Shlomo Zalman Auerbach, Minchas Shlomo 1:25) ruled that today, one cannot be lenient for this matter, since mevushal (pasteurizing) is standard procedure, and does not significantly affect the wine. There is also a question of whether pasteurizing is sufficient to be considered mevushal, since Rishonim (and the Shulchan Aruch) note that this requires actual boiling.
Most authorities are still lenient concerning today’s mevushal wine, since the enactment was not made on mevushal wine, and because of additional reasons for leniency today (see Iggros Moshe, Yoreh De’ah 3:31; Teshuvos VeHanhagos 2:401).