Joel McHale Says Alleged Don Lewis Doc Doesn't Exonerate Carole Baskin

Joel McHale knows a thing or two about 'Tiger King' -- and he also knows this ... just because Carole Baskin's husband might still be alive, she's not totally off the hook.

We got the comedian/actor at LAX and asked him about this big revelation in the 'TK' sequel -- namely, what the documentary asserts is a legit form from the Dept. of Homeland Security that alleges Don Lewis is actually alive in Costa Rica. Not just that ... but apparently he's chillin'!

Our camera guy asks what a lot of people thought when they saw this ... that Carole has been vindicated from all the claims of having something to do with his disappearance/presumed death.

Joel -- who hosted the original 'Tiger King' post-show special -- says not so fast ... as he sees this in a different light, and actually convinced our photog to come on over to his side.

Check it out ... Joel says that if this document is legit -- and if DL is, in fact, alive in CR -- then it's still a harsh indictment of Carole, especially if she's known about it all along.

Now, in Carole's defense ... she seemed to know nothing about this alleged DHS form -- and has maintained since the beginning ... she did her part in trying to find Don, and had absolutely nothing to do with his disappearance in the '90s.

The former 'Soup' host thinks this doesn't really paint her in that fond of a light. And, he even has suspicions about how the guy could've remained missing for so long if he is actually out there somewhere.

BTW, he isn't saying Carole deserves any sort of retribution -- but he does insist this latest development wouldn't make her any kinda saint.