There are blonde people from Mexico as well.
Some, not many. And just because there are some blond people in Mexico does not say anything about Garcia and Tarrio.
Being Hispanic does not mean that you cannot be a white supremacist.
But being non-white makes that non-credible.
Look at Enrique Tarrio, recently convicted of sedition, along with a bunch of other serious offenses.
I do not think he is a white supremacist either. Or that "Proud Boys" are. Right wingers? Yes. But those are two different things.
It's interesting who is 'white' and who is not. I used to work with a bunch of people, largely from the Middle East, but not entirely--there were south Asians and Eastern Asians in the group as well, and a few (white) Americans. Except for the Americans and myself, no one in that group would be called 'white' by other Americans. Most (but not all) of the Middle Easterners would have been highly insulted if you had insinuated that they were not white. A few were much more dark skinned. I had not realized that there was a 'color scale' until my boss, who had much darker skin and his wife, a lighter skinned woman had a child. The lighter skinned quietly, with some satisfaction, would say about the baby: You can't even tell! because the child more closely resembled his mother. Later, when I was promoted and needed to interview replacements for my former job, they absolutely refused to hire a very beautiful, intelligent, well spoken, very qualified black woman---because she was black. I found it amusing that the women who were pursued within that place of employment were always blonde. Thankful, but amused. Another American co-worker, a brunette, was quite pretty, much prettier than the other women who were considered 'desirable' but who would have been seen as quite....average had their hair not been blonde.
My father, who like me, has dark hair/eyes and who tanned very easily and spent a lot of time outdoors, so was perpetually tanned, once picked me up from the airport. He was uncomfortable with who I was working with, because of their perceived race/color. He very cautiously asked me 'how dark are they' and I immediately touched his forearm and told him they were about 'that dark.' Which was true of most but not the ones who were quite dark skinned. A couple were lighter than my father's tanned arm.