Not sure what is meant by "aikido in football".
I don't think, for example, that there's too much value in teaching ikkyo, nykkyo, etc... to football players, as the increased performance for football would be minimal, if at all.
If the idea is to teach the principles of aikido (blending, moving off line, keeping one point, etc...) to football players, that may have some value. I would hesitate to say anything stronger than "may have value" because as I see it, the goal isn't to produce more effective aikidoists, but rather, more effective football players. (Or have I misunderstood?)
Which means that those aikido principles would have to be incorporated into traditional football training in a manner that would not only be understood by football players, but not resisted by the football players or conflict with other training either. And at this point I would have to bow out of the discussion. I'm not familar enough with technical training in football to comment if aikido principles aren't already taught, albeit with different terminology, drills and methods, in modern football or how/if they could be incorporated.
I think aikidoists should try out the skills of a d-lineman. Not only does aikido enhance sport performance, sports skills can enhance aikido practice.
I think I disagree with this. Having known collegiate football players, I've never met or seen an aikidoist who has the necessary athletic ability to be a d-lineman, at least not on a collegiate or pro level. There might be some aikidoists out there, but I bet they would be former football players. Even the guys that warmed the football bench were extremely formidable athletes.
In general, I'm inclined to disagree that aikido enhances sport performance or sport performance enhances aikido. In my mind, those are two different skill sets. I may agree that the general physical preparation (GPP) for sports helps aikido as it creates a better athlete, and I would also say the reverse can also be true. For example, a gymnast would be better than an average person at aikido because their gymnastics training has made them more flexible, given them better balance, better preproperception, etc... And that an aikidoist would be better than an average person at gymnastics for the same reason(s). That may seem like splitting hairs, though.