That's the problem with time travel. You can't really keep it a secret. The mechanics are based on the laws of nature in theTrek universe and because of that, will be eventually discovered by other races. Or enemy spies will manage to steal that information. It's like the atom bomb: once the genie is out of the bottle, you can't put it back in.
It is eventually discovered by other races - and leads to the Temporal Cold War which covered multiple eras, timelines and dimensions, and dozens of species and was ultimately about how the technology should or shouldn't be used.