A greater danger to athletes are regimes that persecute homosexuals. Without the special function, profiles would be visible via the so-called explore button. This allows a user to see which profiles are online all over the world via a map. Regimes with a hostile attitude to the gay community can't sneak a peek at which athletes are looking for a little fun with the Olympic feature.
“We want Grindr to be a place where all queer athletes, no matter where they come from, feel safe to interact with each other while in the Olympic Village,” said Jack Harrison-Quintana, Grindr for Equality president (a division of the company).
It's Grindr's first time doing this at an international event. However, there are also countries where the explore function is disabled anyway, to protect vulnerable users. Think of countries like Saudi Arabia or Iran.