I think I understand the general gist of where some of this feeling is coming from, so despite being delighted with the judgement, I have some empathy with transpeople -especially the very young, even though I am certain it is unfounded.
Much of this worry is expressed in the same online spaces where many vulnerable minority groups are feeling uncomfortable rumblings of exclusion in a changing political climate; there really is a sense of the old "First they came for the..." in many spaces, with strong anti-immigration sentiments being expressed increasingly freely, disdain for the disabled finding previously unseen traction, activism in more niche areas such as climate being more harshly punished and DEI initiatives being under scrutiny (I'm a mother of a disabled young person, who works with refugee communities so I feel this change in the landscape quite keenly).
If, as a transperson, one identifies strongly with being part of a vulnerable minority group and not just simply as the opposite sex, I can see that one might feel worried that the SC ruling represents a thin edge of an exclusionary wedge.
I also think these flames are cynically fanned by TRAs, exploiting fear and vulnerability, when re-evaluation and reassessment of new ways to ensure needs are met (third spaces etc) would be much more productive.
But I think it is disingenuous and lacking in imagination to say that we simply can't understand why some transidentified people are feeling uncomfortable. Many are really young -school kids- and part of the identity is about belonging to a persecuted minority.