Can a middle age person with no job and bad health get on the Affordable Health plain?

The Affordable Care Act is a law, NOT a health plan.

If your friend is still within the time window from losing his insurance and he meets the income criteria, he may be eligible for a SUBSIDY which would help pay for some or all of an individual health insurance plan.

They can but try.

He does not need the Affordable health care act.

https://hhs.texas.gov/services/questions-about-you...

Why doesnt he purchase insurance through his state ACA program?

You don't need EXPANDED Medicaid to qualify for MEDICAID. You only need a certain income level. He needs to start there if he has no job right now. Every state has Medicaid. EXPANDED Medicaid is for MORE people, but that doesn't mean he doesn't qualify now. 

Yes.  However, if he has no income or his income is low enough to qualify for medicaid in states that expanded medicaid (even if he doesn't live in one of those states and doesn't qualify for that reason), then he cannot get the federal subsidy and will have to pay full price.

yes he can.         

He should apply for medicaid in his state.

In theory, yes, but I can't answer for any state except my own, California.  The wheels of bureaucracy turn more slowly in some places.

The answer is absolutely yes.  He has a limited number of days after a life change to apply to Covered California, and losing his job counts as a life change.  If the disability is temporary, I suggest he go to coveredca.com and run through the application.  For his income, he should put what he earned last year.  If he puts in an income that is too low, he will be directed to MediCal (MedicAid), which is absolutely free, but at his age, they might try to recover the cost of his plan from his estate should he (heaven forbid) die.  The Kaiser plan under Covered California can be as little as $1/month if his income is under 4x of the poverty level.  That doesn't get much, there are still copays, except for things like free checkups and vaccinations.  But if he has to go to the hospital, or has something severe, Kaiser will cover everything except the first few thousand.

If it looks like he'll actually have little to no income, then he should go for the MediCal, which is absolutely free, no copays, no limits on when someone can enroll, but subject to the cost recovery mentioned above.

If he's permanently disabled, he should look at Social Security Disability.

Perhaps, depending on his income.  The online application will tell him what he qualifies for. There is no pre-existing condition restrictions on marketplace or medicaid plans.