This low level change need a fix: twinks (with xp blocked, not ganking noobs in xp-on bg) shouldn't scale up. There is a reason why they twink at said level.
On a side note, Heirloom gear + enchant on xp-on BGs will always stomp new players. With or without scaling. Period.
Now about screwing real twinks.
I play twinks 70 atm.
Before jumping on saying I kill lowbies and ungeared players: nope. My experience is OFF and only play agains other 70s BiS toons. Not leveling players. So haters take your rage elsewhere thanks.
This change means my 70 twinks and their scaling will turn 74 in BG screwing my crits. It means re-gearing completely as a 74. Problem is, 74 gear is bad (beside engi 72 googles). It means: my bracket, my fun dies with this change and most will move on in upper or mostly lower brackets (19 or 64 is my guess). And god knows the fun of many already died with baseline resilience and 90% resilience 70 healers.
If this goes live I kan kiss most of my fun goodbye.