I think that would be regarded as sensible parenting on both sides. I've seen Palace shirts in Brighton before. I usually tut and ponder on the cheek of it, then remind myself that it is less affronting than seeing the usual United and Chelsea shirts. At least these folk support what is, or was...
The only BYF I know is the Brighton Yoga Foundation.
Although calling it a day after running two Palace fans out a pub and rocking a few cars is understandable in the light of the collateral damage to the beer.