Yeah, and Linux is compromised if someone kidnaps Linus Torvalds family in exchange for creating a backdoor in the Linux kernel.

The security is created by humans to be used by humans; so nothing is truly safe if <insert random circumstance> happens; and anyway, for cases like yours the hack would be found after few days when any of the people in charge of the compiling realizes that the check-sum is spoofed and would advice anyone to update the OS after the issues is taken care of.