Reflect the LEDs!

[tsh]

Yes, it's non-inductive.

Additionally, both antennas are on the other side of the PCB, so the keymat wouldn't affect it anyways.

Well, you really need to be concerned if it is resistive - by the same argument as reflecting the LED light, power is only dissipated by resistance. I agree it is unlikely to have an impact across the PCB, but this might be relevant in other situations and seems everyone gets RF wrong at one stage or another!