Spence was intimidated by the moment. He will only improve as he gets more big fights. Imprudent to bet against Spence. And you are selling Brook short. He is talented and hits like a mule.
maybe he could grab a eurotitle and defend that a few times with success, instead of getting a world one and losing it straight away with his first world level defence.
Like some others have already said, unless it's on medical grounds, no. Brook has still a lot to give, just not a 147 imo