But, if we take Unam Sanctam as being true...and the Roman Catholic has to....then the Roman Catholic has to believe that people who identify as transgender can be baptized.
There's no disagreement the lay Roman Catholic can have on this as their "authority", though not the Biblical authority, has ruled on this.
Still wanna play?
Based on the lack of answer as to what authority in Catholicism there is to correctly interpret Scripture for Catholics, I can only presume there is none, or none recognized as legitimate.
Which then leaves the lay Catholics in the same position as the non-Catholic that they condemn, of reading and interpreting Scripture for themselves.
If they don’t recognize any authority they are willing to submit to or accept interpretation from, then they have no choice to to do it for themselves if they are going to read Scripture.
However, if there is no authority to interpret for them, then there’s simply no point of the Catholic reading Scripture at all.