For clarity, I assume you mean friendly to retired military? Essentially all love ex-mil who are not participating in the reserves (I know USMC retirees, unlike some other services, cannot do reserves and would not normally be able to volunteer for temp recall).

A few small mom-and-pop regionals may have shied away from older retired mil in the past, but in this climate I don't think anybody would hesitate.

With you they know about how long you'll have to stick around to get your competitive FW time, so they know their ROI. Regionals today will hire mil guys who will likely be around for only 12-18 months.

Not much. Really what's on the table is six years of AD pay, bennies, and retirement credit (assuming no stars on the horizon). If you're going to retire now regardless, you won't lose much by taking a swing through the regionals for a year or three. Worst case, you decide you don't like airlines and go get a regular job (don't base that decision on regional new-hire experience, majors are significantly better).

If it's a choice between staying for 30 or airlines, that's a little bit harder.

But legacy hiring is only beginning to ramp up so unless you have significant skeletons you should be a shoe-in. Six years is a LOT of airline seniority to give up, given the current and projected rate of hiring. Rumor is that big-three are loosening recency standards for O6+, giving them credit for good performance in duties which limited flying opportunities.

Hiring today is largely limited by simulator capacity, ie they can only move people around and hire them as fast as they can train them.