Why is it much ado is made over RF interference from clevis -control horn ,etc., metal to metal contact, but no caution is raised about metal to metal contact in retractable landing gear?

Metal to metal is only a problem if there can be lots of movement between the two items. A tight joint with no play seldom exhibits a problem. If that can not be obtained, a flexible jumper wire securely attached to each part which electricaly shorts them together will keep any rf from being generated.