Is there any other special traffic not destinatated to the RE that will be handle by the RE whatever is transit or not....?
A: There should not be. Even unknown Source MAC is sent through transmit, and then also copied to RE for learning. No packet should hit RE and then be forwarded as transit traffic.
This is indeed strange behavior. I am wondering if an EX4200 works the same? I assume you may not have ability to test this. There are operational and implmentation differences between EX4300 and EX4200.
I would suggest you work with TAC on this one, as I believe switch should not operate the way you say it is operating. Yes you could probably work around this with an explicit pass filter for routed traffic, prior to hitting the drop filter.
Do you see the same behavior on a L2 VLAN, no RVI/SVI? Just wondering.