Surely the idea would circulate the water in the pond, which provides some benefits ?
The leaf blower itself wouldn't do anything for your pond, you couldn't get air more then a ft below the water surface, now if you had a way to hook it up to a bubbler down deeper in the pond it may have some aeration benefits, but I can't imagine the blower itself lasting very long trying to push any amount of air with any resistance, they are mostly built to move a volume of air at no resistance.
They make a solar aeration system that is actually designed for that purpose, but I cant imagine a leafblower setup being anywhere near cost effective. but then Ive been wrong way more times then I care to admit.