It all comes back to the fact that the most important voter to politicians is the potential "swinging voter". They will always try to appease someone who just might just give them their vote, but should you be so stupid as to publicly throw your lot in with one party or another, you are immediately forgotten. If you are an opposition voter they avoid you like the devil, if you are "one of theirs", they have little need to appease you as you are already in their pocket. The more "convinced" you appear to be in your selection, the less attention you will attract.
Voters, whether they are Unionists or not, should be playing the politicians off against one another, as they do the public. Anyone who publicly proclaims allegiance to any political party, has just given away most of his power to achieve anything politically.