I believe proper etiquette would be for congress to mandate it first, then the FAA would regulate, unless of course an executive order trumps it all.

Today I was on a 145 and I'll say it would be a bit difficult to assume the position for those pax of the larger size .
Second a/c I was on was a UAL 37-800/900 series and the only problem I could see was placing said pax. of larger size in the frigging exit row in particular row 20 when said pax was clearly too large too fit through the exit .
Airlines need to start getting serious about who they seat in an exit row.

Lack of response to what I posted yesterday leads me to beleive that it may have been over the top and if it was perhaps someone will step up and say so.

Not necessarily. But, it's just not that simple. First, the lawsuits. You're going to have an airline tell someone they're too fat to do X? Good luck. Second, what's your metric? Do you expect that the gate agents will have a tape measure/BMI calculator with a "you must be this thin to sit in the exit row" sign, and switch folks that don't meet the criteria? Or just use their "best guess"?

To prepare for an accident, few things I do-

1. Do count the seats, but don't count on them being in the same neat little rows after the crash.
2. Look at the safety card, and memorize how to open the doors. ALL of them. The mechanism is almost always different on different types of airplanes. Even know if there's a cover over the window exit handles. Recite it with your eyes closed, as either a) this may be a night flight or b) the cabin fills with smoke often, and rapidly. You'll be glad you did if your butt is on fire and you need to open that door and get out NOW.
3. In reference to #2, don't expect a flight attendent there to help you.
4. Don't cross your legs during takeoff or landing. If there's and accident and you get crushed, it helps prevent breaking both legs.

God forbid it ever happens, but you'll be trapped in a tube most likely on fire with a bunch of people who have no idea what to do and haven't paid attention to anything during the safety briefs.