They knew the issue when they got the order. They probably ran it by the city informally then. Anyone routinely engaged in this kind of heavy industry is going to have an understanding of the city's disposition to these sorts of things and know who they need to run these things by. Now that all the details have been tentatively agreed on they're formally asking.

Alternatively, it may have been a case of "if we get permission great, if we don't then we'll install the masts elsewhere for an extra several mil."