Krum is a mining industry veteran now consultant with over 30 years line and corporate management experience and underground mining experience and his opinion differs to yours. Yours is a claim is an argument from authority. This is what that means in case you were wondering...
"Anargument from authority(argumentum ab auctoritate), also called anappeal to authority, orargumentum ad verecundiam, is a form ofdefeasible[1]argumentin which a claimed authority's support is used as evidence for an argument's conclusion. It is well known as a fallacy, though it is used in a cogent form when all sides of a discussion agree on the reliability of the authority in the given context.[2][3]"