Hello Livio,
In general I recommend asking these kinds of questions in the partner
support group, where there are many other data providers and Google
folks:
http://groups.google.com/group/google-transit-partner-support
You can also contact Google support staff directly via:
transit-...@google.com
To answer your questions, though:
1) Google doesn't replace working feeds with newer that don't pass
validation, as that would tend to break the service for users.
2) Google doesn't automatically extend expired feeds, as that would
run the risk of providing riders with incorrect information, if the
new schedules were substantially different from the old ones.
For more details about your particular case, please contact
transit-...@google.com
Thanks,
Joe Hughes
Google