sysstat used to have a 'cron' USE flag to control whether /etc/cron.d/sysstat was created, but it went away at some point. This is still documented in, for example, https://wiki.gentoo.org/wiki/Sysstat
I'll attach a simple patch that re-introduces a cron USE flag as +cron so that the default behavior after applying will be the same as before, but, gives the user the option to turn it off via portage.use.
This is related to, but not quite the same as this bug: https://bugs.gentoo.org/show_bug.cgi?id=531032
This change would be an effective workaround for that bug.
Created attachment 422036 [details, diff]
Re-introduce a cron USE flag, default to on.
We've been up and down this path since forever. Search for bugs about app-admin/sysstat needing to either install or not install cron files or the right type or make it optional. It is now truly well-trodden and I am hesitant to "fix" it again because it's bound to break it for others.
The ebuild uses the upstream defaults now and you can override those locally by setting CONFIG_PROTECT or INSTALL_MASK or a combination.