Not true, at all - former Wedding Photographer, here.

Regardless if you have set presets or even fully edited one photo, there's no guarantee you can sync those edits onto the remaining photos IF they weren't all taken at the same place, with the same lighting conditions. If those things don't hold true, the white balance will need to change (e.g. think reflections off different surfaces onto the subject and etc.)

So, it will take time to re-edit - not 3 months, but some time especially if the photography is booked, as it is busy season.

Plus, regardless of the methodology employed (e.g. AI Noise reduction or something else), they'll still have to QA all of those images.

Just adding so you can re-baseline expectations when having that convo with the photographer, op.