Jose wrote:
I have been told that it is illegal to fly IFR in an aircraft that has
an operating IFR rated GNS 430, whose database is out of date, =even= if
it is placarded INOP, placed in the OFF position, and the airplane, even
without the 430, is otherwise legal for IFR.

pedantic answer:
The restrictions are spelled out in the Approved Flight Manual
Supplement. Most installations of a particular make and model (like
Garmin 430) have identical AFMSs, but since the AFMS is approved on a
aircraft-by-aircraft basis, it's possible there can be differences.
There is no general answer to your question. You have to read the AFMS
for the specific aircraft.

Dave