Do I need a Health Insurance Certificate after traveling to Laos on an O-A visa?

Off hand I’d say since your in the country on your approved extension already, and reentering on a reentry permit I’d think you’d get no grief at the border. I’d say it’s a lot different situation than your initial entry without an extension on that visa type.

Out of curiosity, where is a 70+ yr old supposed to get insurance from?

Sadly, there is no way to really tell how they will interpret the rules.

The way it is panning out IS

If you got the O-A visa BEFORE the mandatory health insurance requirement came into effect (Oct 31st) it seems they are not asking for proof of insurance when you enter the country..

BUT

With that being said, no one can really tell you how it will work when you go to stamp back in.

IF you are asked and can't provide proof, you will get stamped in on a 30 day visa exempt entry instead of the O-A visa.

AND

You are correct, If your friend is on the "free second year" of his O-A visa (meaning the VISA itself is expired and he's just on a year entry stamp) he WILL need a re-entry permit to get stamped back in to the country for the remainder of his current entry stamp.