Nope, sorry, you're wrong here. But I'm pretty sure we're talking about different things. The Sayaka Rule I'm talking about has everything to do with perceived relevance.
DR1: Sayaka is introduced as Makoto's main love interest and very heavily featured in promotional materials for DanganRonpa. When a demo of the game is released, they go as far as to completely write out Sayaka's death (Hiro is the first victim instead), having her act as his assistant. When the actual game comes out, she is the first victim.
DR2: The Ultimate Imposter/Twogami is again shown prominently in early promotional material. He's instantly the odd man out being the only 'returning' character from DR1 in the game. The game instantly gives him importance and gives him the role as leader of the group and he begins to introduce his own mysterious plot line into the game, only to be cut off when he is stabbed to death and becomes the first victim.
DRAE: We're going double duty here: Yuta was introduced as a prominent character in promotional materials (although really all of the in-game Kill List Targets were) but we only know him for about five minutes before he accidentally violates the rules and gets executed. On the villain side, Masaru was introduced in promotional materials as the leader of the Warriors of Hope but he's the first of them to be penalized and thrown out of the game.
Of course, the person who was actually the first victim
still fits the pattern overall.
Also, I don't know why you think Yasuhiro couldn't have died first, he's a character who recently got development in a light novel side story, he's an acceptable target because very few people exceptionally like him (in fact I have seen some people outright hoping that he dies), and he's still a DR1 survivor so killing him off still send the message of "Even a DR1 survivor can die, no one is off-limits" which it clearly didn't set for you since you outright say that you think Makoto and Kyoko are off-limits.