Voting across community lines promotes non-sectarian politics
Colum Eastwood looked, at best, half-hearted in his response to Mike Nesbitt's suggestion that unionists and nationalists might spare a vote for each other.
And Nesbitt himself had seemed a bit sheepish when he said that he would give a second preference vote to an SDLP candidate who hadn't a chance anyway. Nesbitt lives and votes in east Belfast.
All of which suggests that this wasn't meant to be a joint-backing for a radical new endeavour to rise above sectarianism, but just a bit of a blunder. Well, sometimes that is how great ideas get their first airing. There is a plain logic in nationalists and unionists voting across community lines. Each, if they get to be top dog, has to work with a party from the other side. So why not exercise a preference for one or other of the contenders?
Until now, the firm unionist position has been that unionist voters should vote for pro-union parties, all down the card. The logic of this is that they would rather have Jim Allister scowling at them from across the floor and Sinn Fein at their sides.
The SDLP is not actually going to overtake Sinn Fein at this election, unless a miracle happens, so this can all be dismissed as theoretical, but it is more than that.
The message to the electorate is that these parties prefer a sectarian carve-up to a more imaginative array.
Indeed, Sinn Fein and the DUP guaranteed that is all we would ever have when they banjaxed the spirit of the Good Friday Agreement at St Andrews and wrote into the Agreement that only the biggest parties in each community could fill First and Deputy First Minister posts.
So, Eastwood is disinclined to flex the boundaries of nationalism, to signal that he might be a reformer, because he has little to gain right now.
But the fact is there are SDLP voters who will not give second preference votes to Sinn Fein, and might be coaxed to give them to the UUP. And there are UUP voters who wouldn't cross the street to pour a cup of cold water over Arlene Foster if she was on fire, but they might give a second preference to the SDLP, if wooed sensitively, and ultimately if they thought it was going to make any difference. Which it would in the long run, because it would express a preference for non-sectarian politics. People would like that.