In any other situation, it would have been fine. He could discreetly use his magic, or wait for someone from Camelot. It would have been fine. But Morgana had constant eyes on him and his cellmate. That was the other problem. He didn't want to risk revealing his magic to someone of Camelot, or who might blab to Arthur if and when he arrived. Nor did he want to injure who he was with. He couldn't risk Morgana seeing either- that would only enrage her further. He'd have to wait it out.