I think this is more a cultural (and maybe also generational/sub-culture) difference than objectifying.
Still I understand your point and did hear similar thoughs (even from some anime/gaming convention visitors) in regards to maid cafes.

However, everytime I had the chance to talk to a maid (which was always at a convention and never in japan nor in a commercial cafe/place) and asked them why they dress up as a maid. The answer was always "for fun", often because they like to cosplay/creating cosplays or interacting with people.

In my opinion maid cafes, cosplay and also this schools experiment isn't to objectify the girls or even with a sexual though behind it. Even if this doesn't exclude a chance of sexy/cute attraction, but to be honsest that's also the case if a cute girl dresses normally.
A outfit should never define how we treat any person and harasement/discrimination is always bad no matter what's the reason behind it.

Still, I don't know the situation there and everyone can have his/her own opinion about it.
Also, in the rules for registering for the course (on the official japanese page, according to bing/google translate), they mention that the school may remove students that doesn't follow the instructions of the staff (which propably includes the maids themself, since they are employed).

Thanks for sharing your opinion!