To come back to your intended discussion about the usefullness of Judo:
Imo Judo is a great Martial Arts which has (like a lot of Gi based Arts) the problem of only partially transitioning to MMA. That doenst mean its bad or anything, e.g. Bjj does just fine (but also seems more willing to give up the GI atleast in the US).
That being said i believe a lot of fighters could benefit from Judo training. It definetly has its applications in the clinch and gives a grappling oriented fighter more options to work with.
Is it a must-have like wrestling or kickboxing? No. But imo it could work pretty well as a secondary base to the "standard" MMA skillset.
On the other hand achieving a black belt takes a lot of dedication that a mixed martial artist might not be willing to put in, if he hadnt started Judo as a child.
Also Judo seems to have its own problems like banning single and double legs (sorry i dont know te correct Judo term) from olympic level.