Because he doesn't know wtf he's talking about.
The ACA, which was signed into law in 2010,
explicitly prevents health insurance companies from denying coverage, charging a higher premium, or refusing to cover treatment for pre-existing conditions. The only factors in play when setting premiums are the applicant's location, age, tobacco use, and plan category (bronze, silver, gold, and platinum).
If an insurer tells any of you they're denying coverage, you should report them to your state's Department of Insurance.