I hear a lot of talk today about xenophobia. Is it really phobia if you have something to be afraid of?Answer: it depends on the definition. Some definitions merely reference fear, whether justified or not. Others require the fear to be "irrational" or unjustified, which seems to be the definition Maher is using.
If most immigrants vote Democrat, it is rational for Republicans to fear them. Depending on the definition used, that fear may or may not be phobic.
Brits who voted for Brexit have real concerns about overcrowding at NHS clinics and in the subsidized housing occupied by less affluent Brits, not to mention in the job market.