My reading of the rule is that it only affects gymnasts who were DP, then competed a state meet in another program.
Simple work-around ... don't go to Xcel State if they are going to go back to DP, especially if they made the minimum qualifying score in DP to move up to the next level.
The current petition process only allows gymnasts to petition to L7 or below, but the new one for former DP allows petitioning into Levels 5-10. This would allow a former DP who moved to Xcel to come back in a higher level, even if they aren't 12 years old yet, as long as they met the minimum age for the level.
There was some discussion regarding entry into the Development Program from alternative programs, but nothing was decided, so the current rules SHOULD remain in effect unless or until they come to some decision.