Why the need to mount a partition with nosuid when noexec is present?
Solution 1:
According to the mount man page
noexec
Do not allow direct execution of any binaries on the mounted filesystem. (Until recently it was possible to run binaries anyway using a command like /lib/ld*.so /mnt/binary. This trick fails since Linux 2.4.25 / 2.6.0.)
So, this looks like it's old advice from when noexec didn't stop all binaries from running; at least they weren't run with root privileges.