(1) Your question is answered by the Ran DH Ee. The Ran explains that the difference between Rebbi Tarfon and between Ovadia was that the owner of the field still suspected Rebbi Tarfon of stealing his grapes all year long. Therefore since Rebbi Tarfon was very wealthy this was considered as if he owed money to the owner since he was able to pay up and remove the suspicion. It follows that avoiding paying this money by announcing that he was a Talmid Chacham was equivalent to benefiting from the crown of Torah.

In contrast if a Talmid Chacham utilizes his standing in order to avoid paying things which he anyway is not obligated for this is not considered as benefiting from the Crown of Torah. This is because the Torah gave the Talmid Chacham the right not to pay taxes and the privilege of taking precedence in business in the same way that the Torah granted Terumos and Ma'aseros to Kohanim and Leviim. We learn from Ovadia that a Talmid Chacham is allowed to tell others who he is, because he is only obtaining for himself what he is legally entitled to. This is not the same as Rebbi Tarfon's case because the Torah does not exempt a wealthy Talmid Chacham from paying money to remove suspicions from himself.

(2) In fact thieves also are allowed to take figs after the knives have been folded away. However the landowner now thought that he had caught the thief who had been stealing his grapes all year long. He knew that what Rebbi Tarfon was doing now was permitted but he thought that if this person eats my figs even at a time when this is permissible, it probably means that he is the one who has been stealing from me all year long without a Heter. The Maharsha writes that he was not actually intending to kill Rebbi Tarfon, because he knew the Halachah that a thief is not culpable of the death penalty, but rather he was trying to frighten him so that he would confess that he had been stealing the grapes.

Shabbat Shalom

D. Bloom