Just as bad? No… I can’t get on board with that, and I have no moral objection (or even opinion, really) on bisexuality or open marriages or flexible group-sex arrangements, nor do I care about traditions or the effects on children or other bullshit arguments trotted out in anti-SSM screeds.
There’s an existing and well-established right for two persons to form a legal bond, which comes with numerous privileges. I don’t care in the least if the couple is in love (and wouldn’t want a government agent to have to evaluate the extent of said love); their emotional bond, if any, is of no legal relevance. Until quite recently, it was assumed that the couple would be of differing genders, but this left out people who wanted to pair-bond with someone of the same gender. Since legal distinctions based on gender have pretty much fallen away, there is no purpose in extending to one couple the right to legally bond (and gain the aforementioned privileges) while another couple is denied.
I don’t see how this does or should have a bearing on arrangements involving three (or more) people, regardless of their individual genders or orientations. It’s not like some three-person marriages of a particular configuration are permitted, while other configurations are not.
This is no way implies that I think two is some magical or perfect number ordained by God or whatever. It’s just that existing marriage law is written with two people in mind. Anyone who wants to advocate for polygamy at the very least should have some ideas on how it would be legally applied. This is a serious and critical step, not to be glossed over. So there’s a man in a marriage with multiple women (a configuration that is certain to be among the most common in a polygamy-legal society). The man dies. Do the women have any continuing legal obligation to each other? Suppose two of the women are bisexual (and thus in addition to being conjugal with the man, they were also with each other) but the third women is heterosexual (and had sex only with the man). Is there (or should there be) any legal significance to the third woman not consummating the marriage with the other two? Can the two bisexual women annul the marriage to the third woman, or was the marriage dissolved when the man died?
And this is just one scenario. Are distinctions to be made for group marriages where anybody can have sex with anybody versus ones where the pairings are more limited?
I don’t care in the least what arrangements the spouses make among themselves. My concern stems from instances where the spouses end up dealing with government agencies. Does spousal privilege exist and thus none of the spouses can testify about the others? Do they file their taxes as one big legal entity? If one of the spouses is a veteran, do his or her benefits extend to all the other spouses?
These are not issues where the courts or legislatures can just make up stuff as they go on a case-by-case basis.