Possibly, i just thought it was edmure being weak after Jamie threatened to throw his heir over the battlements.
I think Edmure was shown to make bad decisions early on when he lost Robs element of surprise
Its a good theory though but i can't see how having the Freys turn against the lannisters would be in any way helpful to Jamie unless they can organise a 'red wedding' style pre emptive strike to take them out in one go.
I personally think we were just being shown that Edmure is more interested in his self than his house



