If the new FM doesn't defend the bill - which Reagan has said she wouldn't as it'd be too costly and likelihood of winning is low then that leaves the SNP with 2 outcomes:

At worst, they've made promises to trans people in Scotland they knew they couldn't keep & now won't defend, but have been using the talking points as examples of Westminster blocking Scottish law making powers, so by doing that they look like they've used emotive trans issues in a bill, they made a bad faith attempt to pass knowing it would fail - just to generate talking points to further their own agenda of independence.

At worst - it makes the SNP look like incredibility incompetent legislators when it was known this bill would fail from the start from waaaayy back: https://commonslibrary.parliament.uk/research-briefings/cbp-9079/ So they made no good faith attept - just ploughed on knowing it was futile, making promises they might come to abandon.

Shambles whatever the outcome.