I'm glad I found this thread. I thought my game is glitched in a new way (in addition to its existing glitches).
My dynasty heir's twin brother has lived 8 days past his second notice, so I thought my game might be broken. After reading this thread, I checked and he does have the Active trait, darn it.
@Playalot So I can expect this sim to have an elder lifespan of no longer than 20 days? At present, he's 87days old (based on his immortal twin's age bar).
Since it's a dynasty file, he can't 'accidentally die," either. :-(