If Mark thought he would remove the chip inserted under his skin later, he had another think coming. Bayliss and MI6 were far too smart to let that happen. Unlike a dog's chip inserted just under the skin, Mark's chip wouldn't be skin deep, it would be inserted much deeper inside his body, close to a vital organ so any attempt to remove it surgically or otherwise would be extremely risky, assuming he knew where it was located.
That meant the operation to insert the chip would require a general anaesthetic.
Recovery took longer than originally anticipated, delaying his departure.