It sounds like what he is talking about is what people do every election cycle. They change their party affiliation of who ever is in the primary so they can vote. When a liberal is in office, and there is a Republican primary, the liberals usually vote for the one that they feel would have less of a chance to win.
Me, I am a registered independent and had to briefly change my party affiliation to Republican so I can vote in the primary. I voted for who I feel has the best chance of winning. Now that the primaries are over, I changed it back to independent.
Republicans do the same thing in the Democrat primaries when a Republican is in office. It is a normal cycle.