As the grandparent points out, although the article says that, the actual regulation does not. The regulation says you have to prevent side ejections, it doesn’t say how. You can read it yourself:

https://www.law.cornell.edu/cfr/text/49/571.226

> Ejection mitigation countermeasure means a device or devices, except seat belts, integrated into the vehicle that reduce the likelihood of occupant ejection through a side window opening, and that requires no action by the occupant for activation.

Lamination and side airbags seem to be the way it’s usually done today, but nothing prevents a better way.