Code of Federal Regulations, Title 36, Parks, Forests, and Public Property. President wasn’t even involved in this. AG Barr wanted time move the perimeter back in the morning after the vandalism of the church the night before. Protecting public property falls within the realm of the federal government. And the judicial precedent is set regardless of how it was set. For example Marbury v Madison established judicial review, but judicial review doesn’t just apply to court appointment processes.
The SCOTUS case you were citing doesn't seem applicable to the facts here because here there is no license or permit etc. required to be protesting. (at least not that I'm aware of) That's what I was talking about. I also said that POTUS doesn't have the authority to make the laws. Whether it was Trump or Barr isn't really that significant to what I was saying. (and really, it isn't knowable due to the adminstration's low credibility, esp. after the bullshit about the use of tear gas) They are both executive branch officials, and I was talking about the separation of powers.
The larger issue, which I wasn't even talking about, was whether or not the actions taken were legally and morally justified. Perhaps they were, if what Barr said on Face the Nation is true:
BARR: They were not peaceful protesters. And that's one of the big lies that the- the media is- seems to be perpetuating at this point.
MARGARET BRENNAN: Three of my CBS colleagues were there. We talked to them.
BARR: Yeah.
MARGARET BRENNAN: They did not hear warnings. They did not see protesters--
BARR: There were three warnings.
MARGARET BRENNAN:--throwing anything.
BARR: There were three warnings given. But let's get back to why we took that action. On Friday, Saturday and Sunday, OK, there were violent riots in- at Lafayette Park where the park police were under constant attack at the- behind their bike rack fences. On Sunday, things reached a crescendo. The officers were pummeled with bricks. Crowbars were used to pry up the pavers at the park and they were hurled at police. There were fires set in not only St. John's Church, but a historic building at Lafayette was burned down.
MARGARET BRENNAN: These were things that looters did.
BARR: Not looters, these were- these were the- the violent rioters who were- dominated Lafayette Park.
MARGARET BRENNAN: But what I'm asking about--
BARR: They broke into the Treasury Department,--
MARGARET BRENNAN: --on Monday when it was a peaceful protest.
BARR: I'm going to- let me get to this, because this has been totally obscured by the media. They broke into the Treasury Department, and they were injuring police.
But really, I don't believe him because I have seen no evidence to support what he is saying and I have seen evidence to suggest that what he is saying is false. His credibility is pretty low after the tear gas bullshit anyway.