Chad, it's always best rather than pontificate on absurd rancid places such as Facebook, to talk to someone who has actually done it. Thats where I step in. They are correct but if you want to spend money on lawyers, knock yourself out.
First point is completely invalid it that situation hits. For sure it's a gamble, as long as you understand thats fine. But it takes many many years to save in premiums what a triple heart bypass surgery will cost you and given the average age of retirees is gods waiting room area, it's a gamble that probably won't pay off unless you die in your sleep. Second point - absolutely agree. Third point, hmmmm many people aren't aware that thai insurance companies cannot or will not reach across to your country for medical records, which is why if you have a clean record in Thailand you're good to go. It's what they will go on. (So if you have a minor(ish) element never let them reccord your details as you're then on their radar. Fourth point, not sure where you are from Nick but if it's the UK, the waiting list will kill you long before you get to see anyone that can save you. The NHS is a basketcase.
Most insurers will have age limits but there is the odd one that will insure up 99 years old BUT unless they contractually agree to a set percentage rise each year, once you get old they can simply ramp up your premium to an insane level to get rid of you. Point 2 - I've never heard of an annual medical being covered, apart from the initial medical which is their interest. Also do you really want them to get an update every year on you which could whack up your premiums? Best to get it done seperately and privately in my opinion.