Another victim of the PC police
For God's sake. People have moved from being outraged by movies they haven't seen to being outraged by movies that haven't been made.
If Facebook and Twitter had existed in the 80's and 90's I guarantee Rain Man and Forrest Gump couldn't have been made. "Tom Hanks will be starring in a comedy about a mentally challenged man? Shame on you, Tom Hanks! What were you thinking!??". Instead the movies got made and both won Best Picture.
Depicting a condition and demeaning that condition are NOT necessarily the same thing. Even movies with a lot of comedy--as both Rain Man and Forrest Gump have. People now are too shallow, too knee jerk, too prone to playing the moral policeman to see that distinction.
As it is, the Reagan movie was apparently far more of a political satire than anything else---not unlike Farrell's satirical depiction of George W. Bush. There seems to be no evidence whatsoever that it was trying to make fun of Alzheimer's disease itself.
But we'll never know because we live in a second Victorian Age. All of our entertainment can't even be misperceived as offensive by the rabble. So bland and inoffensive we have it.