I really enjoy following Spacex and Starlink but I am far from an expert on 5G. I do however believe that they are aimed at different markets. (At least at the moment) Starlink is aiming to be a home internet provider and they will at least initially target areas with minimal internet infrastructure or no infrastructure at all. I believe that 5G is aimed at the cellular market and will thus not be competing directly with Starlink.
If you are talking about actual signal disruption and not market disruption I have no idea what potential consequences could arise though I do know that the FCC and other agencies have been trying to clear certain satellites from certain frequencies.
It is a shame that Musk will never let Spacex go public it would be an exciting company to own a portion of.