This is just not true.
As the article points out, Section 1(ii)(B) has absolutely no provision requiring activity to be outside of the United States. Read it through:
Section 1. (a) All property and interests in property that are in the United States, that hereafter come within the United States, or that are or hereafter come within the possession or control of any United States person of the following persons are blocked and may not be transferred, paid, exported, withdrawn, or otherwise dealt in:
(ii) any person determined by the Secretary of the Treasury, in consultation with the Attorney General and the Secretary of State:
(B) to have materially assisted, sponsored, or provided financial, material, or technological support for, or goods or services in support of, any activity described in subsections (a)(i) or (a)(ii)(A) of this section or any person whose property and interests in property are blocked pursuant to this order;
Look closely at this part of (B):
to have materially assisted, sponsored, or provided financial, material, or technological support for, or goods or services in support of, any activity described in subsections (a)(i) or (a)(ii)(A) of this section
The requirement is only to assist, sponsor, or provide support to someone described in (a)(i) or (a)(ii)(A), which describe people who are "in whole or in substantial part, outside the United States."
What it does NOT say is that the person providing that support must also be outside of the United States. That's what the EFF article is talking about.