Question: what was the point of jon snow being a targaryen mean?
Answer: For being a Targaryen he could and had to pass Judgment on Daenarys. For being a Stark he had the swing the sword. That was the reason Jon needed to know he was Aegon Targaryen. For him to know his destiny, and his legal duty, to save the people of Westeros and kill Daenarys.