The gemara tells us a rule that although one is not allowed to believe loshon ho'ra, they must at least take precautionary measures. The gemara cites a pasuk that considers Gedalia Ben Achikom guilty of the murders of Yishmael Ben Nesanya (who was the one who killed Gedalia himself), because Gedalia could have protected himself by following the advice of Yochanan, and did not. Similarly, the gemara tells of people who had a reputation of murderers who made a request of R. Tarfon that he hide them. R. Tarfon said that if he doesn't hide them, they will be killed by the government (even if they aren't actually guilty), but if he does, he himself will be in danger for protecting fugitives. Therefore, he compromised by advising them where to hide without playing an active role in hiding them.
Rashi explains that R. Tarfon was correct in not assisting them in hiding because "maybe they killed and it would be forbidden to savve them". The Rosh (also in Tosafos HaRosh) questions this. How can the concern for the possibility that "maybe" they killed, create a prohibition on R. Tarfon to save them? Therefore, Tosafos and Tosafos Harosh conclude that he was concerned that his safety would be compromised if the government found out that he was hiding them. He was afraid that perhaps they were murderers and the government would hold him responsible for protecting them. Tosafos HaRosh writes emphatically that one may one be "choshesh" for loshon hora by protecting himself and others from harm. One has no right to be concerned or believe the loshon hora beyond what is necessary to protect people from harm. The Ya'avetz asks, why is this an example of being concerned for loshon hora, even if R. Tarfon would know beyond the shadow of a doubt that they did not kill, he would have the right to refuse helping them in order to protect himself? Perhaps the situation was that R. Tarfon knew that the government wouldn't harm him unless they looked into the matter and found these people guilty of murder, so the only concern for his safety would be if they actually were murderers.
It seems from Rashi that the concept of being "choshesh" for loshon hora doesn't simply entitle you to protect yourself, but rather it is a halachic requirement to not take action that would be forbidden if the loshon hora were true (such as saving an alleged fugitive). The Chofetz Chaim (6:10:25) paskens like Toasfos that being choshesh for loshon hora cannot go beyond what is necessary Ch protect oneself and others.