Vans maintains RV airplanes were not designed for IFR. The reason for two static ports is to eliminate (or compensate for) static errors caused by sideslip. That's why the ports are tee'd together at the bulkhead.
As I stated "one of the reasons" and the other would be what you stated.
Fact is, that this set up up still leaves you with 2 static sources, imperfect if one is plugged up but more accurate than a cabin pressure source I would argue.
My point was that static port failure (plugged) simply does not occur at least not during flight and if it happens, say at the paint shop, you should be able to notice on the first pre flight check after it come out of the paint shop.....
I know many of the rules were established eons ago for good reasons but
better solutions supersede many of these rules.
Most of our GPS equipment shows altitude, ground speed and even vertical speed and many such as my Garmin 696 even display it in an old fashioned
dial configuration. Using such information in case of a "static line/port failure"
would certainly be at least as good or better than cabin alternate static air.
I am not suggesting that you go fight the mighty rulers of mandatory alternate static sources and gascolators, simply stating that such rules are long out dated.