I think that's going too far the other way. I think maybe an open ended question like "What do you think of your bf's views on x?" could be ok. Where to go from there would depend on her response(s).
I stay out of my children’s love life. It’s none of my business. I’m here to support my child. You interfere if you like, it often doesn’t end well, your relationship will suffer.
I don't have any children, sometimes I wonder if I ever will. My eldest sister has 2 daughters, and I can certainly agree that sometimes her comments on her children's viewpoints weren't always received in the best way, but I think that not commenting at all is worse. I also think that asking questions is perhaps the least intrusive way of broaching a subject. If they react negatively to a question, at that point, it might be best to just leave the issue alone.