Enabling autosave when plugin disabled

You need to remove the action that WC added by doing something like

remove_action( 'admin_print_scripts', array( $this, 'disable_autosave' ) );

There are two tricky parts to doing that well

1. This needs to run after WC add its own action
2. you need to figure out how to find the exact same $this value that was used when the action was added.

I would still advice to get in touch with WC support because only they might guaranty that disable_autosave is a stable function name that they are unlikely to change in the next version