I don’t believe that the WP Plugin Directory Guidelines prohibit a plugin from “forcing” itself to be auto-updated. I just think it is bad practice to take that choice away from the site admin/owner.
I can understand plugin authors wanting to make sure that site admins/owners are always using the latest version of their plugins…but that decision should really be in their control (and ultimately, it is…since they can always define the AUTOMATIC_UPDATER_DISABLED
constant to true and then no auto-updates will happen, and there are several other means to disable auto-updates across the board).
If you want to encourage site admins/owners to auto-update your plugin I think the better means would be to add your plugin to the auto_update_plugins
option (which is what the Auto-Update UI does). But if you go that route, be sure you don’t corrupt the value of that option…as doing so would interfere with all of the other conscious choices the site admins/owners have about whether to auto-update other plugins.
If you don’t mind my asking: why do you want to force your plugin to be auto-updated?