Mercury treads and Tahm Kench's belly

SO i was thinking today, merc treads is supposed to reduce all crowd control effects by 20% except for suppression, stasis, and airborne effects. I'm not sure how Kench's devour is coded, but i feel like if you have merc treads and you get eaten by an enemy kench, he shouldnt be able to hold you in there for the full duration. Thoughts?