I don't see anything wrong with requiring someone to specifically state that they want to exercise their right to remain silent. Otherwise, when do the police decide the person wishes to remain silent (how long must they remain silent before the police decide the person wants to exercise their right to remain silent)?
The opposite is to require them to affirmatively state that they waive the right to remain silent. My opinion is that such a requirement would lean too far towards the rights of the suspect, and not give the police enough leeway to solve crimes.
The old time criminals all knew the drill - "I ain't saying nothing without my mouthpiece (lawyer)."
Go into the world and do well. But more importantly, go into the world and do good.