No chance I take that offer. This Bell situation is ugly. If he comes back and isn't traded by Tuesday, there's a 2 week roster exemption the Steelers could use that, I think, would keep his pay down for those 2 weeks. I'd not be surprised if they do that, whenever he comes back. And there's no guarantee he comes back this week. This could still go on for a while.
And even though Bell really is one of the best backs of his generation, Conner has been better than fine. I'm not certain they hand the reigns right back over to Bell whenever he comes back. What message would that send to Conner (who likely is their guy next year no matter what)? What message would that send to the rest of the team, many of whom have (a) publicly expressed frustration with Bell over this, and (b) expressed support for the job Conner has done?
Long story short, never a bad idea to explore a trade. And I do think it makes sense to explore trading Conner because there is more uncertainty there than typical. But I would NOT be selling him at a steep discount, which is exactly what you'd be doing by taking that offer -- especially because you don't need WR help. Smart offer by the other GM. Not one I would accept, however, even straight up for Cook. You throwing in OJ Howard too?? C'mon....
If you really are intent on trading Conner to avoid the floor potentially falling out, canvas the teams in your league who are fighting for their playoff lives. They're in win now mode, and don't/shouldn't care about 3 weeks from now. If you find one that has a player like Dalvin Cook or James White or Sony Michel (heck, maybe even Zeke or Gordon given that they're on a bye (and Gordon was dinged up last week), or perhaps a panicky Kamara owner), that's your target. You should even get a bit of a + coming your way too in the Cook/Michel/White scenarios.
Just my two cents. Good luck.