Possibly because lawsuits challenging the power of the President to impose tariffs under the Emergency Economic Powers Act are underway.[1] GOP support for Congress taking back control of tariffs is building.[2] At some point, Congress or the courts will take his toys away.
[1] https://www.newsweek.com/trump-tariffs-hit-lawsuit-group-his...
[2] https://thehill.com/homenews/senate/5236142-congress-tariff-...