Again, the number of people effected, actually trying to enter the country at the time, was quite low, as in under 500 at inflated counting levels. The numbers indicated at 100,000 included everyone possibly effected, and remember that this was a ninety day suspension, not a permanent ban and that, too, is well within the discretion for the President, whether it is Trump, Obama or Roosevelt, to determine. That problem, green cards and returning people with visas, was corrected before the end of the weekend. Chaos, not really. Bad implementation, definitely, but it was corrected fairly quickly.
If cancelling the visas of 100,000 people trying to get into this country from countries that have no way to document their own citizens, and are known hotbeds of terrorist activity as determined by the previous administration, potentially prevents the loss of one life here or injury to one person here I'm all for it and would support it no matter who the President is at the time.