I would much rather remove it and put in a fancy tile shower with maybe a hotel style frosted glass partition.

If you think it's okay for them to stay, then let it slide for 4 months and take your chances with any repercussions.

This will set proper expectations with the tenants as well.If they learn you make exceptions to the lawn, then they may begin to push their limits and see what else you will let slide.

The windows on this house and on my residence nearby have brittle plastic inserts holding the glass on all four sides on the exterior.

This is a cheap temporary solution so the tenant doesnt drive you crazy in the meantime. our windows slide left to right not up and down so there is nothing to hold a window unit in place.. it would be dangerous to put a window unit..his apartment runs length wise and if he did open the window in the front of the apartment ( living room dining room) and his bedroom in the back it would cause cross ventilation but he refuses to open the windows for safety reasons.. we are in a nice area and he is on the second floor.. our living room dining room have ceiling fans and we gave them 2 large stand up rotating fans.. the lease does say there is no compensation for a temporary lose of heat or a/c.. so would that still leave me liable for his hotel bill?

Great idea, I'll take two glasses please.

But then again, I'm a glass-half-full person who also screens his potential tenants closely, follows my gut and makes certain to tell my tenants and any co-signer(s) what I expect and don't accept. 

the door in the picture is not a solid wood door, the broken panel is just a thin veneer and it is a single glass door.there is no security or insulation with this doorthis door should have been replaced with a steel door long agomy recommendation is to change the door together with the frame, otherwise it is almost impossible to make the new door (called slab) be a perfect fit with the old wood frame that most likely already warped.

This tenant is too new to let him slide.

Took the over door off, took the smooth-top glass top off to clean under it.