Michael didn't rush to establish a Link of Loyalty with everyone. He finished the Link, asked them how they felt, and provided them with the Soultrait Symbols as requested.
Some Divine Lifeforms were impatient, but Michael ignored them. Nobody was allowed to disturb him as he slowed down deliberately whenever someone spoke up or bothered him. Once everyone realized what Michael was doing, they stopped moving and waited impatiently for their turn.
Michael had no idea how much time passed, but all 600ish Links of Loyalty had been formed at some point. The Links weren't strong or anything, but that wasn't needed. The Divine Lifeforms didn't trust Michael and forced themselves to sign the Link of Loyalty – some at least – while waiting for the Heads to kill Michael and end their suffering by returning their freedom. Michael was fine with that thought, though he wouldn't allow anyone to kill him.