Well, you know that 2010 was the first year there were "tea party" candidates. And Rand was one of the very few to win. Leaving Ron Paul completely aside, one would think that Rand Paul would be a natural for a RNC speaking slot.
I think you might have a case, that you could say something that could make me agree with you, but you aren't making that case.
Rand Paul, on his own merits, deserves a speaking slot. He is a US Senator who is popular with Ron Paul supporters and with others who don't like Ron Paul. I'm not arguing that being Ron Paul's son didn't get him most of the way to being US Senator.
Of course, Romney putting out anything but a RINO parade might be surprising.
You haven't made the argument that Romney is such a Liberal Republican, a country clubber, a RINO that anything other than RINO at the RNC is a shock. You can also argue it's a shock that Romney is letting any Paul speak because he does not want to help Ron Paul in any way.
If I argue that it's natural and obvious that Rand Paul, a US Senator, popular with different types of Conservatives, should be speaking, you can argue that Romney would rather hurt specific Conservatives than help his own chances of winning. That's a decent argument and may very well be true.