According to Sunnis, there are two different types of Tawassoul:

1. Tawasoul when a person is alive.
2. Tawasoul when a person is dead.

The 1st one is not Shirk according to Sunnis. Such as in the hadith above. Umar used to recourse when the prophet was alive. After his death. now the recourse to the honor of his uncle who was alive at that time.

Moreover to explain why **Sunnis** consider it is shirk, recourse according to **Sunnis** is different from recourse according to **Shia**. **Sunnis** call Allah and recourse by someone(i.e: *O Allah cure me for the sake of this person*). While according to **Shia**, you can call the name of the person with the intention that he will recourse in front of Allah for you (i.e: *O' Hussein cure me*) which Sunnis consider it shirk.