Ah I see what you mean, fair point - I'd agree that doesn't really work!
TBH my 2-node system was a simplified version of Corosync which I've worked with a bit, in that you allow quorum if you have half+1 of nodes up - so 4/5 up will maintain quorum. The highest-node lives rule is just a tie breaker in the case of a half/half split which the 2 node system always has when one node goes down. Good point though, that rule alone is definitely not a good idea.
TBH my 2-node system was a simplified version of Corosync which I've worked with a bit, in that you allow quorum if you have half+1 of nodes up - so 4/5 up will maintain quorum. The highest-node lives rule is just a tie breaker in the case of a half/half split which the 2 node system always has when one node goes down. Good point though, that rule alone is definitely not a good idea.