You are in part wrong.
I would advise you to read up on the founding of Texas. There were many Mexicans involved in the revolution that gained freedom from Mexico. When you visit the shines of the Republic of Texas founding, there are old line Mexican Spanish families that played a significant role in the founding.
The same is true in New Mexico and California. If you recall, Zorro, a semimythical character was actually of Spanish heritage. California was founded by Spanish
Your argument fails once people realize Spain is in...wait for it...Europe...and just chock full of White people.
So to be an “old line” Spanish family is to be a family of White people.
First of all, I am a native South Texan and well aware of the “revised” history of Texas.
Second, you stated “there are old line Mexican Spanish families that played a significant role in the founding.”
There was a HUGE different between the Spanish and Mexicans.
Texas was settled by SPANISH land grants....not Mexican land grants.