About the spouse: The SEHI deduction can include the spousal part B cost. A retiree isn't getting Medicare B through their ex-employer. If publicly available coverage is being paid by post-tax deduction from the retirement, I call that "doing the banking" but that is not subsidizing it (unless they are paying only a partial cost or being reimbursed for the cost?) or on offer by the ex-employer (think of how employers can reimburse corporate shareholders for their ACA policy costs, and then the shareholders have it as a possible qualifying cost:

https://www.irs.gov/pub/irs-wd/1228037.pdf

It's a different story if the person would qualify for Medicare, but delayed signup because they still are covered under an employer's private coverage.