In the largest university system in my area, they have an active practice of trying to buy-out professors who have ~15 years of experience so that they leave before their pensions vest. In exchange they hire younger non-tenured PhDs who work their asses off for less money. The older profs sometimes leave for private industry or a private college having pocketed 2-3x their annual salary but without the lucrative pension which attracted them to the job in the first place.
The biggest drawback to this practice IMO is that there's a steady 'brain-drain' of the best profs shortly after they've really become established and start to really draw money for the university in the form of large federal grants. But the personell department understands salary and liability (pensions) and rarely considers the value added (grants, experience). Consequentially, the system remains second-tier even though there's a perennial push to move up in the rankings.
Yup, buy-outs are generally going to be a terrible way to reduce headcounts/total payroll, since you'll preferentially remove the most productive people who are confident they can go find another job somewhere else, while the people who know they're already getting more than they'd make at another job are the ones who are least likely to accept a buyout offer.
This is interesting b/c DH's federal job is on the bubble right now b/c Trump's budget request slashed funding for scientific research. DH is adjunct at the local university, and when they heard the possibility that his job would be gone next year, they immediately offered to try to hire him on as faculty (he's got Full Professor status) and implied they would try to match his federal salary or close to it. The reason is the value that DH brings to the dept...he brings in some of the most money, and supports and graduates a very large number of grad students, among the highest in his department (in fact just won a prestigious college-level award last year). So I'm not surprised they'd be loathe to lose him.
However, your story makes me think that, were push to come to shove, they might not actually offer him a full professorship with retirement and health benefits, but some sort of highly paid 'temp' position.
Congress makes the actual federal budget, of course, and I doubt Trump's moronic attempts to gut funding for scientific research will mostly come to pass, so probably DH won't have to actually find out if his university is as shitty as some of these stories imply.