Are holding feasts for the deceased on the day of their passing, and on the third day (the "tounisa"), and offering hospitality to mourners, considered permissible acts in Islamic Sharia, or do they contradict it? And is what the man did by refraining from these feasts and distributing raw meat to the poor as charity for his father in accordance with the Sunnah or in contradiction to it?

It is not from the Sunnah (definition) for the family of the deceased to prepare food for people to gather around; rather, the Companions considered it a form of wailing. An exception to this is a guest. However, if the family of the deceased is poor, or if there are orphans among the heirs, then it is forbidden to hold banquets from their money. The man's action in breaking this custom is good. The prohibition specifically concerns gathering in the deceased's house and preparing food for those present. As for giving charity by offering sacrifices or distributing Qurans on behalf of the deceased, that is a good deed.