It may have come down to a trade if Matthew refused to budge.
However, the Horns have done this sort of thing before ... way back in 1999. Their top CB, Todd Lyght, a restricted agent, was locked up in contract negotiations with the front office brass. So they allowed him to negotiate with other teams to determine his market value. He was offered a salary, which the Horns proceeded to match. This allowed Todd to be there to party with his teammates like it was 1999 as the GSOT was first unleashed against the rest of the NFL.