There are literally millions (tens of millions?) of Spanish speakers in this country. Did you consider he might be communicating to them?
What makes spanish speakers so special? Is the senate going to be like the UN now? Everyone with a damned earphone speaking a different language?
The Mexicans may think he was discriminating against them as most of them don't speak correct Spanish. The Cubans speak correct Spanish but not the Mexicans.
I was in a situation in Las Vegas a few years ago and some Cubans were speaking Spanish. My Mexican American friend who speaks fluent Spanish could not understand them. My friend then explained the difference in the language.