This would work in most cases, yes.

I think the point that 'masfuerte' was making is that simplicity and redundancy are _the_ bedrock of reliability.

Even if all the new hardware and software to implement this new security model on avionics busses is 100% open and audited by every laudable computer science / security specialist, it's just _more_ to possibly go wrong. That tends to change how people think about risk (weather rationally or not!)

The paper's method suppresses original message then generates btand-new one, so if the key is easy to find out, then the spoofed message will have a correct MAC. Which means you need a cryptographically secure method to distribute the key, but you also have multiple consumers and you want to be able to replace broken devices too. This sounds like a non-trivial cryptosystem, and assymetric crypto + certificates is one possible solution.