That's not a problem.
I level characters all the time.
There are easy ways to avoid it.
Just do the math.
50% xp bonus NEGATES the amount of time spent dealing with twinks (and then some)
AND
You have people like the friendly Squats <Apex> 60 druid who frequent these grief zones and help by buffing, mass pulling, and generally just helping out anyone trying to level.
It evens out at worst. I die at most once or twice before level 40 to pvp combat. Often times not at all though, mainly because I learned the skills required not to.