My knowledge of Scottish politics isn't the best, but from what I know I'm inclined to think Regan will fall in line - the SNP knew who they would need onside when deciding to piss off the greens and presumably knew they were willing to offer something she'd like. Surely needing to appeal specifically to a mega-transphobe will not have any repercussions. I didn't know Sinn Fein had a similar split re: the more conservative side, but it tracks. Plaid Cymru have a pretty conservative voter base of rural Welsh speakers and I assume it's a similar case for Sinn Fein?

Best case for Labour is probably no election and not having to run another campaign, maybe less for the costs reasoning and more because they wouldn't want the unpopularity that comes with holding power while the UK is running like shit, especially right before a general election which could see them return in Scotland. Although I'm not sure they would win enough to be the dominant party even with the SNP such a mess.