Faint praise, indeed.
Indeed! (and you beat me to it)
I see this as the biggest back-handed slap Rand Paul can possibly dish out.
It would incite open warfare in the GOP if he came out and flatly stated "McConnell is a big RINO".
Instead, he picked one of the biggest and craziest RINOs ever (Specter), and backed off a little. And because very few people had actually compared McConnell to Specter before, Paul's statement only draws attention to the comparison.