A nitpicky review :)

The latest version (1.6) requires JetPack >= 8.8.0 for using JetPack without a connected wordpress.com account. I think it would have been (and still could be) better if you test the JetPack version and use the jetpack_development_mode or jetpack_offline_mode filter as appropriate (though I don’t see why Automattic decided to rename it).

If already using a plugin such as Unplug JetPack, ‘Use Jetpack modules without a WordPress.com connection‘ is checked but greyed out. However, the setting from the other plugin is overwritten by your filter which actually sets it to false (unless it has been previously saved as checked whilst not greyed out). You need to respect the previously set value passed to your Jetpack_Module_Control::development_mode() filter instead of using false as the default (and pass that value to get_option('jetpack_mc_development_mode') as the default).

It would also be nice if that setting was initialized on the basis of other installed plugins that affect it, so after deactiviting other plugins it retained its value. I think you’d actually need to invoke the jetpack_offline_mode (or jetpack_development_mode) filter (or perhaps use the Automattic\Jetpack\Status::is_offline_mode()/is_development_mode() method) to find out what other plugins are actually setting.

Otherwise looks very good and slimline (just one PHP file with fewer than 1,000 lines).