Well, yeah, cuz pig latin's really easy. It's a simple pair of rules applied consistently to a language the speaker has fluency in, using a-for-a substitution and syllable shifting. Speaking backwards is ridiculously hard, there's no set rules, no easy exchange of one syllable for another or shift of order, no consistency or reliable pattern - you have to go through and rearrange every phoneme individually for every single word you use. That's definitely mental agility.
And look I know that big cats can be lazy but I think if you are getting to the point where you are having to dust them than something has perhaps gone somewhat wrong.