Nigel Lythgoe took a fun shot at Simon Cowell ... the same Simon who went after the "American Idol" reboot.

We got the longtime EP of the OG "Idol" Friday on his way to E Baldi in Bev Hills, and he thinks the new judge's panel -- Katy Perry, Luke Bryan and Lionel Richie -- is rock solid.

I DON'T GET IT
OBJECTified

It's unclear if Nigel's heard the promo for our new show, "OBJECTified" Sunday night on FNC, where Simon scoffs at singers judging singers and then targets Katy Perry.

Check out Nigel's review of Simon ... on the Billboard Hot 100 Cowell comes up goose eggs!