You don't suppose people are choosing to live elsewhere for any "political" reasons do you?
I also have a (former) long time friend that went hard MAGA and now wants to move to a state that reflects his political alignment
Texas is not such a state because of their Medicare rules. Medicare is a federal program, but for some aspects of it states are allowed to add additional rules.
First, a very brief overview for those younger or foreign readers who have had no reason to learn anything about Medicare. When you turn 65 and start Medicare you can choose between "traditional" Medicare (also called "original" Medicare) and "Medicare Advantage".
With traditional Medicare the government is the insurer. They provide hospital insurance (called "Part A") which for each hospitalization covers up to 60 days at 100% after a $1676 deductible, then covers 30 more days $419 per day. They will also cover days after 90 at $838 per day, up to a lifetime total of 60 "after 90" days. After all those "after 90" days are used you pay all costs.
They also provide insurance for non-hospital stuff (called "Part B") that covers preventative services at no cost, and a bunch of other stuff with with a $257 per year deductible and 20% coinsurance.
There are a series of plans available to traditional Medicare users offered by private insurance companies that supplement part A and B by covering your part A deductible and your part B coinsurance. The plans are called "Medigap" plans or "Medicare supplement" plans. The federal government defines what these plans must cover but the companies that offer them set the price (and can offer additional benefits beyond what the government requires). There are 10 of these plans, called plans A, B, C, D, F, G, K, L, M, and N. Not all are available in all states, and some of those are no longer open to new enrollees, but generally in most states you'll have a choice of several.
When you turn 65 and first enroll in Medicare you have "guaranteed issue" rights. If you apply for a Medigap plan the company must issue it regardless of your prior health history and they cannot charge you more based on that history or on pre-existing conditions.
Every year there is an open enrollment period where you can change your Medigap plan, either to the same plan letter from a different company or to a different plan letter but you will not have federal guaranteed issue rights (with some exceptions such as your provider no longer offers the plan you are currently on).
So maybe you bought a Medigap plan from say UHC when you started at age 65, because they were the least expensive option for the plan you wanted. But now 3 years later they have gone up and are the most expensive, and also in that 3 years you've developed some expensive chronic illness. You want to switch to another provider for your plan to save money, but they will charge you more because of that chronic illness so that won't work.
So you are screwed...if you live in a state that doesn't provide guaranteed issue rights beyond what the feds require.
Several states do provide more. California, Idaho, Missouri, and Nevada for example provide guaranteed issue during a window each year after your birthday provided you are switching to a plan that has the same or fewer benefits than your current plan. In my UHC example this would mean that every year you could switch to whichever provider had the lowest premium for your plan letter. (I think Missouri is slightly more restrictive...you can change to the same plan with a different provider rather than to any plan with the same or lower benefits).
Some states go even farther. You can switch Medigap plans at any time, there is no restriction on changing plan letters except that A can only go to A and B-N can only go to B-N. New York is similar except I don't think they have that restriction on A <=> B-N.
Bottom line is that if you live in Texas when you start traditional Medicare with a Medigap plan you might get stuck with that particular Medigap plan and provider, at least as long as you aren't willing to move. If you move to somewhere where your current provider does not offer your current plan you have guaranteed issue to chose a new plan available in that new area.