Secret Hitler: is asking another player to choose which card to discard "cheating?"
Yes it is cheating and called out in the rules.

Rules


  Verbal and nonverbal communication between the
  President and Chancellor is forbidden. The
  President and Chancellor MAY NOT pick Policies
  to play at random, shuffle the tiles before 
  discarding one, or do anything else clever to
  avoid secretly and intentionally selecting a
  Policy. Additionally, the President should hand
  both Policies over at the same time, rather
  than one at a time to gauge the Chancellor’s
  reaction. Attempting to telegraph the contents
  of your hand using randomness or any other
  unusual selection procedure violates the spirit
  of the game. Don’t do it.


Additionally


  Discarded Policy tiles should never be revealed
  to the group. Players must rely on the word of
  the President and Chancellor, who are free to
  lie.


Simply put once the election is over the President and Chancellor should stop all communication and move to quickly enact a new policy by following the rules and this should be done in a timely manner as to not give any hidden meanings from the actions.


President draws 3 policies
President discards one and hands the other two over at the same time to the Chancellor
Chancellor discards one of the policies and then enacts the other one.
At this point and only this point can the President and or Chancellor make claims about what policies they had to chose from


As a side note one very important thing to remember is that no matter what side someone is on they are going to make a claim about having no choice if a fascist policy is enacted. Also a claim can easily be made that the Chancellor was given a choice when a fascist policy was enacted and it was just a fascist President trying to make a liberal Chancellor look bad. The key point here is that the claims of what cards each player had to chose from need to be taken with a large grain of salt as you can easily lie about them.