I think if you are fantasizing about doing something... like planing or wishing you really could be doing something... or if your fantasy is focused on a particular someone you know and really wish you could bed... then this is a danger as you say. But the danger is not in the tugging as much as in the fact that you really are desiring to do something MORE than just masturbate.

On the other hand... if you are masturbating to general fantasy with a view to discharging your sexual energy in an appropriate way... then you may be less inclined or "hungry" for an opportunity when one presents because you aren't hanging out for sexual release so disparately.

Is there any evidence that suggests masturbation leads to acting out?
I would think anecdotaly that lots of guys tug who never act out their fantasies otherwise there'd be a lot more illicit sex going on.

Blessings
Cat.