Well since you already can't conceal carry there except in your car, but only when picking up or dropping off your kid, or in the parking lot, and open carry is the only way to actually carry in to the school itself, your argument seems to be "don't do it, or they might ban it and you won't be able to do it."
As far as this "resolution," Ann Arbor can send all the resolutions they want, they mean jack and shit, only the legislature can ban anything and that is not happening, recent history actually suggests the exact opposite. Other liberal cities have previously sent similar "resolutions" like Royal Oak and Birmingham, they get back a form letter politely telling them to piss off. These resolutions mean nothing and are just for show to make the liberals feel like they are "doing something," and placating their liberal anti gun base.
"Stop, or I'll write a letter telling you how angry I am!"