My views are Roman Catholic and conservative and, if you think them distorted, that is your problem and not mine. I am pinging a couple of others, one ELCA and one Catholic to join in discussion as to the nature and background of Dr. Martin Marty.
Dr. Marty is your straw man. I have no doubt that he is incredibly liberal, but that has nothing to do with the subject of whether abuse by non-Catholic clergy would be reported.
Just to be fair I checked into abuse cases involving Lutheran pastors.
Here's an article about a big settlement.
Here's a list of some cases:
Child Sexual Molestation by Lutheran Protestant Clergy
Here's an article from the "MSM":
Abuse by Clergy Is Not Just a Catholic Problem
So there are definitely cases. But as I said before, for whatever reason the magnitude of the problem appears to have been greater in the RCC.