I think it's either dangerous or a crock of shit.
Boundaries are something that I've worked very hard over the past several years to build for myself. And that is what Unconditional Love is to me, love without boundaries. Unconditional, nothing that the other person can do that's too far.
Loving someone no matter what they do? No. You need to have limits, places where someone can go to give cause for pulling the eject switch. Otherwise you're trapping yourself in a situation that all too easily can become toxic.