Can the internal part of a slip-on tub spout be removed to install it as a front-end threaded spout?
You could return it  for the correct one.

I guess my other option is to cut the pipe?

Clean off the pipe with emery cloth, cut the threaded male fitting off  and deburr  the end of the pipe so you do not damage the O ring in the spout.
Now you have pipe you can slip the spout onto.
I do not think trying to remove the threaded part of the spout is a good idea but if you can afford another one if it breaks then go for it.