Most of the software on a typical desktop Linux never runs on servers, so we cannot uses Linux's high level of use on servers to conclude that it is safe to use desktop Linux.

Also, at organizations like Google with a good reputation for security, the machines running Linux that are connected directly to the internet are very carefully configured to minimize attack surface and most of the Linux machines are connected only to protected internal networks.

And Google has an internal team of Linux kernel maintainers that do not for share most of their work outside Google.