Personally I think he regretted his call to use it as, really, the ball was out.
but, shrug, if it was a mistake it was a small one, the ball was arguably in, arguably out, and in these marginal situations the Ref's job is to make a call, he made it, move on ... Don't spend time worrying about it, it's a small thing.
but then Cole goes for the ball! Curses. Now it's a big thing.
OK, having called 'use it' (ie that the ball was in) RP may sympathise with Cole, but it has to be a PK against Cole....
But a YC? when the original call was probably wrong ? Nah... just doesn't feel right .
I could see myself handling this in exactly that way, and afterwards reflecting : 'hmm, shoolda been a yellow. Yup, and that's why I'm 11+1 and not reffing the 6N'