Like in all situations, I think this ultimately comes down to the circumstances and consequences. Rights are, in the end, mere principals which may help us make good decisions. At least, I've never observed a right descend from platonic space and intervene in the real world to prevent itself from being violated. If the benefits are sufficient and the consequences small enough ignoring a dead person's wishes seems like not that big of a deal to me. Its hard to see the point or benefit of misgendering a person after they have died (ceteris paribus) but sometimes a person's private writings are of large value to the rest of the world and they are, after all, dead.