Have you not met these characters? Neither Shiv nor Roman knew the particulars and had to ask Kendall. Remember, Shiv and Roman aren't competent. They have neither the experience nor the smart to really make this thing work. Shiv more on the experience but she keeps showing her ass when needed to make a move. Roman has almost no competency. Kendall has the book smarts and experience, but is an emotionally tormented and weak character.
Again, Kendall had already made his play. Shiv and Roman thought they were still in the running to be the Succession plan. When they learned they weren't, it's a brand new paradigm and they acted accordingly.
Roman was the most conflicted, but ultimately, he doesn't want to be a yes man to anyone but a family member. He doesn't care about where the company's vision, he doesn't care about it's next stage, he doesn't care about the company's corporate citizenship, he simply wants to outdo his siblings and be Daddy's favorite son. That's really all it is for him...... a contest to see who the favorite child is.
I think this is a valid criticism. They children have been made to seem so hilariously incompetent, it's hard to think someone like Logan couldn't have figured this out earlier. They really are shown as morons, even though Kendall supposedly has some skins on the wall.