Why do you think no aid would have reached Mexico?
Plus, religion had no bearing. The Southwest of 1917 wasn’t exactly booming population wise.
No, the assimilation was not possible due to the Second Amendment. The Mexican government knew that.
The Mexican government itself didn't think that much German aid would make it to Mexico through the gauntlet of the Royal Navy.
I wasn't referring so much to religion as to ethnoculture. The Mexican government of the time didn't want to go to the trouble of assimilating by-now Anglo Texas.