Congress Should have taken Action on the Jones Act

  I wondered, when President Trump placed the Jones Act on hold to allow ships not from America to help relief efforts to Puerto Rico, why it wasn't Congress that was acting.
  The Jones Act is an act saying only American ships can be used when transporting goods from one American port to another American Port.
  Why could Congress not have met in an emergency session and suspended the Jones Act? Surely, there would have been enough votes. When it is an act of Congress that created the law, it should be an act of Congress that brings the suspension of the act. We have three branches of government, and whenever possible, the legislative branch should be fulfilling its role, so the president doesn't feel compelled to step in with an executive order. I am guessing that when an emergency exists, he has the right, given him by legislation, to do what he did. (But, I don't know that.)
   Either way, Congress should step in, and do its own job.