This is dangerous and untrue advice. Drones are considered aircraft in the US, and there is no altitude limit or license requirement for something to be considered an aircraft. See 49 U.S. Code § 40102 [0] and explicit FAA regulation of airspace under 400 feet [1]

[0] https://www.law.cornell.edu/uscode/text/49/40102

[1] https://www.faa.gov/uas/getting_started/laanc