As a parent, you should be taking an interest in what your children are doing, regardless of whether or not you like it. My mother does not enjoy baseball in any particular way, but always took us to games growing up because WE enjoyed it. Its just a part of good parenting to take an interest in your children’s interests.
Now, of course, when it comes to halacha, things are a bit different. But if their Rav allows them to listen with their children (specifically in this case for this family), then they absolutely should.
Know your children. Forget about on the derech or off the derech, its important to create a good bond with them for healthy growth into adulthood.