And it's up to you to tell them this bit of information that they have never, ever heard before and decided against for whatever reason because since this is going to affect the rest of your life you should have a say.
Just tell the person to make a different thread.
People have differently philosphies. Some people don't like watching others wreck their lives/make objectively horrible decisions. I personally don't give a fuck about getting into the matters of randoms I've never met and never will meet, but obviously a lot of people on this site think differently.