This is one of those tricky things, highly dependent on context.

If you're talking about Conway's Game of Life patterns, then "gliders" are the 5-cell spaceships that travel diagonally, and all other moving things are "spaceships" but not "gliders". If you call a Conway's Life non-glider spaceship a "glider" you'll mostly just confuse people.

But if you're talking about other CA rules -- especially rules where there isn't any 5-cell diagonal spaceship -- then "glider" is very commonly used to refer to other moving patterns.

For example, David Eppstein's "Gliders in Life-Like Cellular Automata" database was active for decades -- recording spaceships across a large rulespace, not just Conway's Life. It's an accepted generalization of the term, somewhat like saying "Xerox machine" for any old copying machine whether or not it was built by Xerox.

Misue is still use, that's why the source adds the parenthetical to the mis in (mis)use. It's a novel field we can name things whatever we want.