Because now there's opportunity and incentive for the cops to game the situation by arresting a party who doesn't wish to waive their civil rights. Not a good situation. Look what it's done for asset forfeiture.
Bingo. And this makes it ridiculously easy for a cop to plant evidence or come up with a “crime” to charge anyone with.
Alito made the wrong call here.
If they can use this to get around a warrant, why would they go through the trouble of getting warrants?
Alternatively, You’re driving down the road and the cops decide they want to search your home, so they pull you over, detain you by the side of the road, and have their buddies search your residence while they talk to you.
You’re not home to object, what’s the problem?
</sarc>