Fan's Mom Defends Gameday Costume

A Kansas City Chiefs fan's mom is coming to his defense ... claiming that all of the haters who are saying his gameday outfit was offensive need to kick rocks.

Holden Armenta caused a big stir online on Sunday when TV cameras at the Chiefs vs. Raiders game in Las Vegas showed him donning a headdress with a painted face.

Some, including Deadspin, thought the boy was wearing blackface ... and urged the NFL to speak out on the matter -- calling his feathered attire inappropriate as well.

Armenta's mother, however, said on her Facebook page this week there was simply no need for the outrage ... explaining the boy's facepaint actually consisted of both black and red colors -- in order to match his…