I can't answer your question about a sensor but there is no way I would set a function like wing swing to happen automatically. That just sounds like a disaster waiting to happen. Judging airspeed is difficult and even with telemetry telling you the speed it's not like speeding up or slowing down is instant. Imagine coming off the bottom of a loop and airspeed all of a sudden says swing the wings. Now maybe you're too close to the ground to pull out with the wings back or on the way.
Besides that in every video of F14's I have watched nobody keeps the wings swept for long. I've never flown one but it appears that perhaps they are much more of a handful with the wings swept than when extended. Just seems like a bad idea to me.
your mileage may vary.