John Calvin Commentary Acts 19:33

"And they brought Alexander out of the multitude, the Jews putting him forward. And Alexander beckoned with the hand, and would have made a defense unto the people." — Acts 19:33 (ASV)

They drew out Alexander. It is thought that the Jews did not send out this Alexander to plead the common cause of the nation, but rather that they desired to bring him before the people so that he might be murdered. Nevertheless, his Jewish identity made him so hated that they outrageously refused whatever he was about to speak concerning the matter and the cause; indeed, he hardly escaped with his life in such an uproar.

Moreover, it is uncertain whether this is the Alexander whom Paul mentions elsewhere (1 Timothy 1:20 and 2 Timothy 4:14), yet the conjecture seems plausible to me. And if we believe that it is he, let us learn from this sobering example to walk circumspectly, lest Satan carry us away into a similar falling away (defection). For we see that he who was about to suffer martyrdom became a treacherous and wicked apostate.