Which pro-Mexican political causes are you talking about? Which category do you think Trump thinks the judge belongs to... thieves, rapists, or is he one of the "good ones"? If I went to "Trump University" would I learn how to properly see Mexicans, Mexican American and Americans of Mexican descent in the proper and not racist manner (in your opinion) that Trump views them in?
So, again, just for you, Trump claims that some of the judge's rulings were unfair. Then Trump looked for the judge's motivation for the unfair rulings and noticed the ancestry and political causes and concluded that those were were the motivation for the judge being unfair.
My point is, what Trump was doing was not racist. Maybe Trump was blowing smoke in a legal case, looking for attention, pushing back against a legal case being brought during a campaign and for maybe political reasons, etc., but I don't think Trump was being racist.
Too much of the media wanted to attack Trump and claim that what Trump said was that no judge with Mexican ancestry could be fair to him, but that is nothing like what Trump said. It's more than split hairs.