The section of Mathew is understood by mainstream Christianity as a "double prophecy" concerning both the destruction of the second temple and the eventual second coming of Christ. I can understand someone seeing this as moving goalposts until I consider that it could've been quietly deleted to avoid embarrassment if it wasn't intended this way.

Christians have a wide range of views on eschatology, but the mainstream position for a while has been amillennial, which are not the people who get freaked out about locusts and red cows and whatnot.