> This appears entirely unreasonable.

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)

What appears unreasonable is that the reasons must be good.

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"?

Oh, I did notice t introduce the typo. The commenter corrected after quoted.