There were battery incidents back in the day...remember a mod with no vent holes blowing and rocketing the press in top cap and atty...into the users teeth...
When ego's pop for whatever reason....again they blow off one of the ends and turn into a rocket when they have no vents...
The purpose of vents is to direct the venting gas away from you (preferably at 90 degrees, so it also doesnt turn the entire device into a rocket)...
I would absolutely in no way use it....
More importantly you said....
I am completely draining batteries though with the clearo
In a mechanical mod that has no built in protection, this is not adviseable....overdraining the batteries will abuse and stress them and make possible battery failure more likely...you shouldn't be vaping off those batteries when they get below about 3.2V...so you may need to use a multimeter to check your batteries regularly until you get used to recognizing when your batteries are too low (there is a recognizeable difference in performance)...or if it'll fit a kick, that's an option...
Edit: also knowing your batteries are important... ICR vs IMR....ICR **protected** batteries go into thermal runaway at a much lower temperature and the gases they vent are oxidizers (so they burn more violently)...IMR (or high drains) use a safer chemistry and can take a higher temp before thermal runaway...