It'll drowned without O2 in the water/solution.
Not sure what I would be worried about most,
other than exposure
Not experienced with hydro, but i would definitely get that bubble disc, and the air pump plugged back in ASAP. As for the landlord situation, is there no space that he definitely wont be going in to that you can lock up, or be sure to keep him out of? He shouldnt need access to your entire pad for any reason. My advice would be to put them back on your regular schedule when possible in a location you can be sure to keep him out of. Sorry for the situation...that sucks.