KenV - not familiar with the F35 comms suite but think most LPI link are 'aimed' (tight beam) so you'd need to know where the receiver it to hit him. You then have the cost of a receiver and computer to interpret the data transmission in the F16. Not sure what 'passive sensors' you could use to join? I guess maybe an IR missile head once close enough to detect the F-35 low heat trace? Having an orbiting 'controller' would be a bit of a give away something is going on. If you have the air superiority to park a big target in the sky, why use the expensive F-35 / F-16 combo for the attack - you could use any old previous generation bomber (we've got a few we could sell you
)
To me this 'buddy' system looks like a 'solution' looking for a problem. It is almost as though someone has said "we can't get out UAV to operate fully autonomously so we need a mother-ship nearby" and the salesmen have gone "we can sell this as a concept"... (just my cynical view from working in industry now)