Thats exactly the point. By not owning them, they aren't liable. As evident by the Colgan case, the general public thought they were flying on a Continental Flight, with CAL pilots, and CAL standards.

If this proposal becomes law, then mainline carriers will be liable for the regionals they contract. If I buy a Delta ticket, and my brand X regional crashes, my family can sue Delta (and I would haunt them from my grave, just making a point). So that only leaves three options...

1.) continue to roll the dice and operate as-is, and hope to not be sued when the next regional accident happens (or pay out, which sad to say may be cheaper)
2.) fold said regional into the company, under one seniority list, under the same training/hiring standards as the rest (probably way to expensive)
3.) completely get out of the regional game and let them operate on their own. Maybe code share, but not allow them to paint your name on the side.