I suppose it keeps any emulsified coolant/oil from dripping into the front carb. Looks like it vents to the front...hope so.
If it were sealed it'd completely negate the crankcase vent causing more seals to bite the big weenie.
I removed the vent from the airbox long ago, corked the box and and placed a simple filter on the hose to keep out boulders, alligators, ect...that eliminates the problem far easier... Forum peeps sometimes come up with all sorts of 'creative' mods.
Best mod on this bike imo is to swap to a free flowing air filter and rejet btw, really wakes the thing up and eliminates fooling with that evil chunk '0 plastic airbox insanity.
Cheers, you're gonna love this bike.