I agree with you, I think, that Forte should remain a Bear. However, the logic is reasonable . And certainly not moronic, either. Trading Forte for a 1st (which they won't get) would be, I think, widely accepted. Particularly if it is part of a well thought-out plan. Trading him for a 5th, for instance, would be stupid.
I think the argument against dealing Forte is that he clearly has another year or two in him. So, unless they have a RB that they are in love with in the upcoming draft why not keep one of the strongest aspects of your team. With as many issues that the Bears have LT, LB (both inside and out), CB and safety, keeping Forte allows you just that much more flexibility in FA and the draft. Let him go and now they need a RB, too.