Canadian Mountie & Mdd,
Only Lubavitch holds that we are responsible for getting non-Jews to keep the Sheva Mitzvos. Their position is based on a Rambam (which is not quite as muchach as they say), but the rest of Torah world firs like the Ramban that we are not required to encourage the non-Jews to keep the sheva mitzvos, and we certainly aren’t required to enforce them.
You are misreading the Gemara in Chullin (you are mushing together two different memras). All it actually says on the topic is that the non-Jews accepted 30 (additional) mitzvos and that they only keep 3 of them (one of those three not writing kesubos for mishkav zachor). If we are not required (and don’t actually) encourage non-Jews to keep the Sheva Mitzvos themselves, we surely are not required to encourage non-Jews to keep the additional mitzvos they were mekabel.