When a request is made for a new language in translatewiki.net, it can come from many corners. As translatewiki.net is its own project, it does not follow the language policy of the Wikimedia Foundation. Consequently it can happily support languages like Kotava that do not meet the existing criteria and are now supported elsewhere.
It is also up to the developers of translatewiki.net to decide when they make the language available within the MediaWiki software itself. As a rule this is done when at least 50% of the most used messages have been localised.
The Picard language has now been enabled in MediaWiki and, the question will be when the first messages will become available for its Incubator project. New languages are not supported in the LocalisationUpdate extension so this must be enabled in a different way. Maybe this is one of those administrative jobs that just can be requested in bugzilla..