So selecting TV input make the TV change to ARC but deselecting it doesn't change TV away from ARC. That is not correct.
@hgo58, as someone in your camp wrt TV speakers in standby, this is the behavior that offended users like @Wiimer and @harkpabst the most, once they were forced to turn "the toggle" on to maintain CEC power-on.
Moreover, if you take a close look at @Wiimer 's use case, they actively want the TV audio to stay on WiiM output, despite it being dropped, so that the WiiM can use HDMI auto sense to switch back to HDMI when TV is resumed.
I for one am indifferent to this TV speakers + WiiM streaming scenario, since for me the times when I do want both (cacophony) are rare and I can switch the TV by myself. Like you, I do very much want the standby TV speakers scenario, because I don't want the HiFi power cycled and correcting it by hand is too late.
You are the first case I've heard of wanting the input switching behavior. Would you mind terribly if this was not done at first, because it obviously needs to be optional, and you had to switch the TV by hand? The standby feature can IMHO be done with no new switches.