This appears entirely unreasonable.
Normally the reason is not good. The reason is that unit testing is missing or that downstream effects are not entirely mapped out.
Exactly activities that traditional software developers are loathing because they are boring and mentally straining.
Seems a bit strong.
Unit testing can get you some of the way, but its not a full-on all-case guarantee. Sometimes the code is encapsulating some particularly complex system/behaviour. Sometimes the reason is interop/compatilibity issues or some kind of politics.
P.S. you managed to introduce a typo in your quote (were –> where)
This comes directly after they wrote "statements we can't verify".
Why is it that we can not verify the statements, but we can believe the reasons that people will not touch the code base to be "good"?