But I would be inclined to hire the students. There are more funding opportunities for them (NSF prioritizes students and departments fund TAs) and I’m expected to graduate students. In my field (CS), research staff and postdocs disappear too quickly anyway.
1) A brand new postdoc costs $48,432 on the NIH scale in 2018. This author of this article costs $59,736. Their benefits are also about $3800 more. It's not that fast.
2) I agree that experience is undervalued - and said staff scientist will almost certainly out produce them. But the burden often falls in different areas - I'm evaluated based on mentoring students for example, not staff scientists. Training grants exist. Etc. A senior staff scientist is always full freight born by the lab (barring like, really nice retention/recruitment packages).
But I think the real problem is the author isn't some sort of rockstar senior staff scientist (I've known some). Their productivity just isn't there enough to assume that they're 15 grand better than trying a new draw from the postdoc pool.
There is often also an assumption that more senior people will also bring on money, either completely by themselves or by enabling more projects. The (completely idiotic, IMHO) 2 or 5-year cutoffs on some fellowships makes this somewhat more difficult.
I also think experience is weirdly undervalued in academia. I would bet that, in many fields, three random students at $25k/ea are not appreciably better than one highly skilled staff scientist at $75k, especially if the lab actually paid full freight for the students instead of having them subsidized by training grants and time-limited fellowships. This is tricky to study though....