The GPL is a copyright license, based on existing copyright law and precedent. Yes, it is possible for a copyright holder to make absurd claims about the licens

The GPL is a copyright license, based on existing copyright law and precedent. Yes, it is possible for a copyright holder to make absurd claims about the license, but to enforce it, they'd have to convince a lawyer to take the case and a judge to rule in their favor. For what it's worth, the GPL explicitly states that aggregation in that way does not imply that it's a derived work. MySQL (or Sun, or now Oracle) would be laughed out of court. Note also that using code licensed under the (for example) BSD or MIT license does not protect you from some loony suing you for copyright violation.