I do feel like the Press Release should have used sexual orientation, rather than sexual preference. It's not like a choice.
And I could see part of the reason they had to drop McKinley is to save on costs. Even with the guaranteed sixth Season, they have a large cast, and with the seniors leaving, they likely would have needed more people to join the Glee Club. So many cast members, and even such a large main cast, would be expensive to keep going with.
I will say, though, it seems somewhat foolish to have had Marley, Jake, Ryder, Kitty, and Unique all as reccurings with major screen time in Season 4, bump up to regulars for Season 5 but cut down down their screen time down big time, and then cut them all just over halfway through the Season. It seems like a waste of time and effort, but alas.