I must have missed the ownership table in that video.

How much of the company does she own?

She has publicly stated she is a cofounder of the company. In order to qualify for the TN visa there has to be a legitimate employer-employee relationship, and as cofounder, that makes that impossible. At the very least this makes her subject to detainment for possible immigration fraud.

Founders/cofounders are generally legally and legitimately employees of the firms they were involved in founding.

Yes, if she was the sole or controlling owner, this would be an issue. But “cofounder” and “sole owner” are... not the same thing.

This is well established. You can argue all you want but you're wrong.