The dent doesn't look too bad to me. Seems like a reasonably gentle curve to it rather than a sharp crease which would be more likely to lead to a crack. But the bike shop will be able to give a better opinion based on direct observation of it. Unless they strongly discourage it my inclination would be to continue riding it but to keep an eye on the area of the dent. At least it's in a very obvious spot so any further degradation (incl. cracking paint) would be easy to see.

I had something similar happen years ago on my way to college. Rack came off the top of the car at 70 mph on I-94. Broke the rear reflector and put a little scratch in the fender of my Schwinn Varsity.