It is disallowed for federal employees, contractors, sub-contractors, individuals involved in lobbying the federal government and those in supporting or sponsoring roles for such lobbying, as well as any persons engaged in international negotiations and/or supplication with the US government as well as those supporting and/or sponsoring such negotiations or supplication to hire, contract or otherwise purchase or barter goods, services and/or accommodations from businesses, holdings or associated venues owned in whole or part by, or under substantial influence of, or of material interest to POTUS and his top advisors.
This is necessary.