Linux in Android is GPLv2 not GPLv3. The v2-v3 difference is a big deal to some.
Linux developers made an intentional decision to stick with GPLv2 and to remove the "or later version" option, so you can't include it into GPLv3 projects as you can with most other GPLv2 software.
GPLv3 avoidance is why Apple ships ancient versions of Rsync, Bash and Make on its current OSes instead of the current versions, and replaced Samba with its own inferior SMB service.
Linux developers made an intentional decision to stick with GPLv2 and to remove the "or later version" option, so you can't include it into GPLv3 projects as you can with most other GPLv2 software.
GPLv3 avoidance is why Apple ships ancient versions of Rsync, Bash and Make on its current OSes instead of the current versions, and replaced Samba with its own inferior SMB service.