Ehh, I agree with you on the overall post and the gist of your logic, but there's still some things in there I can't nod. Proclaiming Sheamus' past as two 'solid' feuds... maybe so, but they were easily forgettable tbh. Compared to a US title reign - yes, very monotone but Kofi was still fairly showcased, defending his title quite a lot building up his overness a tad, he was one of those midcarders ready to take the next step. Sheamus never had that, but I'm not one to shoot down this instant push of his. I like it, and I wanna see where it goes.
I honestly think this is all circumstantial. There's literally no one credible on the Raw roster to face Cena right now except DX.. or Randy Orton, who've faced 78 times and is now in the process of making Kingston. So while picking Kofi over Sheamus seems a bit hypocritical as you've said, there's no doubt the Raw booking... and the smarks' minds were backed into a corner here.
BUT, I figured smarks would be more open to this since it's not exactly like it's the first time it's happened. The Lesnar effect is lost on people I guess. And heck, even in recent memory Vladimir Kozlov got a megapush towards the World title, but too bad he fizzled out. You're right, some smarks are the ficklest it's astonishing. Not just about this, about everything. They label almost everything predictable... which annoys me, "predictable" is not to be confused with "logical booking". And if the booking was illogical, they'd complain anyway.
tl;dr I agree with you, all circumstances, go Sheamus, etc.