#scarlet shadow

Good question.

For Renly, there's a few things. For one, the Rainbow Guard doesn't have a tradition that it has to live up to, it's an entirely new organization, one that Renly hasn't even completed yet, with no traditions to transgress. For two, Brienne had won a melee, and won a right to ask a boon. To reject it is to say that the royal largesse that Renly offers is not worth anything.

For Sandor, the Kingsguard has actually seen a significant break in tradition already. Ser Barristan, Lord Commander and decorated hero, was dismissed unceremoniously from his position to make room for Jaime. Outside observers would see Sandor's non-knightly appointment that as yet further corruption of Joffrey's court.

Jaehaerys, keenly aware of the power of symbol politics, would be loathe to avoid that problem. He's also smart enough that if this was something he'd desire to do, he'd create a new institution entirely to avoid any potential transgression of religious matters or threats to the aristocracy. Hence why I suggested a third path for Jaehaerys if that's something he wanted to do.

Thanks for the question, Anon.