Acts 19:30

‘And when Paul was of a mind to enter in to the people, the disciples did not let him.'

On recognising the situation, and concerned for his companions who had been seized, Paul bravely wanted to go into the theatre to assist their defence before the people. He was never afraid to put his head in the lion's mouth. But the disciples knew that while Gaius and Aristarchus might come away from the situation only having been roughed up, if Paul showed his face there he was liable to be torn to pieces. He was Public Enemy Number One. Thus they prevented him from going, no doubt pointing out that while he was free his companions were less likely to be in such deep trouble. It was not his companions that they were after, it was him.