They don't do it now. They would do it if a new organized boycott popped up because that's what they were invented to do. Plus Trump will surely utilize it if he ever feels the desire

Assuming law-following (which I realize the current administration doesn't care about), that agency's authority doesn't apply:

"These authorities discourage, and in some circumstances, prohibit U.S. companies from taking certain actions in furtherance or support of a boycott maintained by a foreign country against a country friendly to the United States (unsanctioned foreign boycott)."

So it's about US companies and foreign governments, not individual consumers purchase decisions

Yes I'm talking about in the context of companies, gov'ts, police departments, etc. I know it's not about personal decisions.

One of the biggest hammers to the hypothetical boycott is this office which effectively criminalizes any company from partaking (going so far as to have to prove they considered the boycotted party for all deals / contracts / purchases / etc.)