The reason Derek says "If you are out of the US... police can't make you stop" is that Derek is advocating the commission of a crime:
https://app.leg.wa.gov/RCW/default.aspx?cite=9.61.230
RCW 9.61.230
Telephone harassment.
(1) Every person who, with intent to harass, intimidate, torment or embarrass any other person, shall make a telephone call to such other person:
(a) Using any lewd, lascivious, profane, indecent, or obscene words or language, or suggesting the commission of any lewd or lascivious act; or
(b) Anonymously or repeatedly or at an extremely inconvenient hour, whether or not conversation ensues; or
(c) Threatening to inflict injury on the person or property of the person called or any member of his or her family or household;
is guilty of a gross misdemeanor, except as provided in subsection (2) of this section.
(2) The person is guilty of a class C felony punishable according to chapter 9A.20 RCW if either of the following applies:
(a) That person has previously been convicted of any crime of harassment, as defined in RCW 9A.46.060, with the same victim or member of the victim's family or household or any person specifically named in a no-contact or no-harassment order in this or any other state; or
(b) That person harasses another person under subsection (1)(c) of this section by threatening to kill the person threatened or any other person.
------------
To be clear, such calls do not need to be expressly threatening or any of the various other alternatives listed above. The word "or" means that any one of the subsections, such as section (b), applies. Hence, merely calling someone repeatedly to harass them is sufficient to constitute a crime under the statute above.
There are, of course, people who believe they have the right to commit crimes if things don't go the way they want.