I think they would have still been uneasy that he was a SPOF, even if he had charged a lot more. And there's also a cognitive disconnect if a one-man deliverable costs above a certain threshold.
The SPOF fallacy is always managements favorite way to waste money.
My current shop we had a system maintained by 1 guy, as like 10-20% of his job/time. I can guarantee you he is not paid even $500K.
This of course was deemed bad & risky, so we must engage a set of vendors to deliver a replacement. 2 years, a dozen subcontractors, and 7-figure annual bill later.. and they still haven't replaced 10-20% of this SPOF. Literally spent $5M so far against max $100k of this guys salary. There are still no signs that SPOF can give up the responsibility even next year.
No one has been fired over this. In fact the decider has been promoted.
Both of these issues are often solved by incorporation.
A one-vendor deliverable can cost whatever, and corporations can certainly agree to keep supporting something for a certain time.
Doesn't actually matter if the corporation has one member, and no coherent plan for what happens to the contracts if that person steps in front of the wrong bus. It makes the relationship legible in the way that the contracting party is comfortable with.