Not an issue, unless you are running for high public office.
I don't see this as an issue period.
If someone a Mormon wants to do personal business with firms owned by other Mormons, I don't care, even if they are running for public office. It's their PERSONAL business.
I'm not concerned about a President trying to steer all government business to Mormon-owned enterprises either. Too many laws in place, too many other layers of people he'd have to go through. Even if he tried it, someone would blow the whistle.