there is nothing in the lore that connects that group with the person called auric sunchaser, there are other things in the game that also have the name auric.
on the other hand as you say there has to be a reason to add the character and the reason would be to explain how the high elves joined the blood elves. we already saw auric in quelthalas and we saw that he has the title high elf representative we don't need anything else.