In simpler terms: they want regulation to ENSURE that those routes / cities REMAIN COVERED. You have to have the SAME NUMBER OF PILOTS, if not more, to cover those SAME CITIES / ROUTES / FREQUENCY.
The point is that while great in theory, in practice it doesn't work.
If you can't make money on the existing route structure you have three choices. Either eliminate the route structure, lower your operating costs (i.e. pay cuts), or raise your prices. You could also do a combination of all three.
Now clearly if we take eliminating route structure out of the equation we are only left with two options. Lower costs or raising prices. When it goes from $60 ORD-MSP to $300 ORD-MSP, a lot of people are going to drive instead. Now your load factors go down so you have to confront the same choices again. If again you are not going to eliminate the route you have to again raise fares or lower costs.
The only way that regulation would work in the sense most of you appear to want it to (keep all the routes, keep all the jobs) would be to make air travel like Amtrak and fund it with tax dollars (which already occurs for essential service routes).
If Congress/FAA can't agree (let alone the industry) on whether a pilot can fly at 65 or not do you actually think they would be able to agree on something as complex a problem as this?