Crazy plays often force us to go back to 'first principles, the definitions, and then build up from there. Let's break it down as I see it:
1. It can't be a fair catch, since 2-9-1 defines that as a catch in or beyond the neutral zone for a free kick or beyond the neutral zone for a scrimmage. So that's out (no free kick after fair catch this time!).
2. But it is either a valid or invalid fair catch signal, as 2-9-3 and 2-9-4 put no LOS requirements on this. So if R catches it, we will have a dead ball, as required by 6-5-5. Not a fair catch, but a dead ball.
3. It can't be kick catch interference, since 6-5-6 clearly defines the restrictions on K from touching R or obstructing R as being while the scrimmage kick is in flight beyond the neutral zone.
So I would say, if R catches it, it has to be an immediate dead ball due to the signal (valid or invalid). It won't be a fair catch, so no possibility of free kick and R cannot choose where between the hash marks they'd like to place the ball. No penalty on K, just a dude legally blocking. If R doesn't catch it, keep on chugging - see what happens next.
