That anecdote seems to insinuate the essence of an MBA offers no substantive value, nor does even the achievement of the accreditation itself. It is the timing of the latter which projects the value.
Is that a really low or a really high bar?
In late career, assuming you're doing well-enough that you'd want to pursue an MBA, you'd already have amassed quite a bit of business knowledge from the school of hard knocks, that likely exceeds the theory b-schools can teach (although they can definitely still fill in knowledge gaps say in finance or strategy etc.). The marginal value of the theory is even less if you majored in business in college -- the difference between a BBA and an MBA in terms of coursework is generally not substantial.
In late career, your experience and success (in different roles) is a generally stronger signal than credentials.
In late career, you'd have developed a fairly good network unless you're looking to pivot to a totally different field or industry.
For those looking to switch from fairly pedestrian post-liberal arts jobs, the MBA was huge in many cases.
The networking effect has never been big for me. I'm fine with having gotten an MBA. Degrees like the one I got were less expensive in those days and it landed me in a good place. But TBH, my undergrad (from a good school) has probably opened more doors than my MBA ever did. (Had I gone into finance, the situation might have been different.)
That said, for many in my MBA cohort who had majored in business in undergrad, most I talked to said they weren't learning anything they didn't already know, save perhaps how to use their financial calculators in novel ways.
Lends credence to the 'signaling' of an MBA, more than anything else.
The parent could have used MD (there are some people who switch careers to become doctors in their 30s) and it would be the same... just having a chance to have been a doctor for longer will put you ahead.
Even if you take out the signaling/credentialing value generally, absent someone trying to make a real career shift (which becomes more difficult as you get older), it's not clear what an MBA--rather than maybe a couple of focused classes--buy you after some point. (But, for that matter, a PhD or other new degree probably buys you less too at some point.)