You might want to have your Uncle read some of the basic books on NLP (see my prior post).
Once he understands the techniques that were used on him, he will feel better about himself and realize why he was duped.
Some folks are more susceptible than others to this type of brainwashing—not their fault.
I haven’t talked to my friend since the inauguration, but I’ll bring it up with him. Hopefully the fact that nothing happened will be enough to get his uncle to move on, but it may not be enough.