Yes, it is; while the idiom standing on its own implicitly includes a leading “at least”, it is also idiomatic to use it in exactly the way used by the grandparent post, in an explicit contrast with better, where it comes with an implicit (or sometimes explicit) leading “merely” instead of “at least”.

It's unnecessary, though, and makes the point harder to read. "It works even better" would be a perfectly sufficient description. "It works not as well as but better" is an unnecessary rhetorical flourish.

The misdirection is being used as a rhetorical device — you're supposed to feel a brief confusion when you get to the colon; it's then quickly resolved.