All this is stupid. What they want is to prevent anyone from introducing the concept that there might be other viewpoints that are as valid as theirs. And, the ones that are "strongest" in the cancer shut out those that are just regular publishers or that sometimes pio-sneer. If the hounders start initiating the rules that only the strongest are allowed to marry, that will create a situation where any children are even more likely to be totally deprived of any fun instead of those who are allowed at least a measure of fun.
Taken correctly, the scripture does have some validity. But, "bad associations" should be taken to mean those who insist that everything you do is something they tell you to. Different belief systems do present a challenge, just as interracial, intercultural, and inter-age group marriages do (that is, those where one person is a different race or culture, or is significantly older or younger than the other). But, that should not be an absolute barrier. Differences in these areas can be resolved. It's when one belief system is so flimsy that it needs drastic measures to preserve intact, along with a tyrannical system to impose such beliefs, that the problems become severe enough that any inter-marriage should be taken with extreme caution.
True bad associations would include political and corporate leaders that like to force or defraud people into believing something that is harmful, religious leaders that exert force or extreme pressure to get people to comply, and those members that are in it for the power. Such people are not generally pleasant to be around for extended periods anyways, and most regular people would not be attracted to such bad associations anyway.