...put an end to an outdated law that prevents women from getting paid more when they outperform their male colleagues.Right off the bat, that should sound a little fishy, because the big problem women face with compensation isn't that employers refuse to pay them more than men, it's that they don't get paid as much as men for the same work—and McConnell opposes legislation to try to fix that problem.
Moreover, even if Mitch had correctly diagnosed the problem, there is no law that explicitly forbids women from getting paid more than men. Even if there were such a law, the proposed legislation he cites wouldn't have any impact on it, because the legislation is merely designed to drive a wedge between unions and their members—or, in the case of right to work states, to allow employers to give employees an incentive to not join a union—by allowing employers to pay certain employees (male or female) more than contract-specified wages.
Technically, Mitch's legislation could let employers pay some women more than some men, but it would also let them pay men more than women—and really, which do you think is more likely to happen?
The bottom line is that Mitch McConnell is, unsurprisingly, full of it. But it is worth noting that he's feeling the heat, because even though his proposed remedy might fail the laugh test, it's clear that he at least wants women to think that he's on the right side of the debate.