This is fairly silly, for two major reasons:
1) Labour have a huge majority. Labour currently hold 45 out of 57 councillors (see the graph below), the Mayoralty, both Parliamentary seats and the London Assembly seat that covers Hackney. Over the last four years, the Tory group has been an utterly ineffectual opposition - this year, they didn't even bother to put an amendment to the budget. In contrast, despite being on her own as a Green councillor, Cllr Mischa Borris put a fully costed amendment to the budget - and would have done more if she had been part of a Green Group. Hackney needs more progressive and effective opposition to Labour, not less!

2) Hackney has an Executive Mayor. One of the main arguments that the Labour Party used when pushing for the centralised system of an Executive Mayor is that it would no longer be problematic if the Council ended up in no overall control - after all, the Mayor gets to pick his own Cabinet however he wants. They can't have it both ways - selling the Mayoral system as an antidote to hung councils, and then spreading scare stories about hung councils once we have a Mayor!
As this graph of the results last time (for parties who are standing in 2010) shows, it couldn't be tighter in Clissold ward. On May 6th, voters will have a choice. Add a few more Labour councillors to a Council already run by them - or take your opportunity to elect a strong, progressive and coherent voice of opposition, who will hold Labour to account for the next four years.

Just to end, I should add that I find Labour's whole emphasis on this issue disappointing. It focuses on the 'horse race' rather than policies. The Greens are pushing Hackney Labour on social justice, sustainability and local democracy - perhaps it is no surprise that Labour councillors don't want to talk about these issues on the doorstep, but instead resort to trying to scare people into voting for the 'same old, same old' once again. I don't think it will work this time.