I didn't think small business were subject to that law.
I haven't found anything that precludes small businesses from complying. Here's the definition of employer from the appropriate US Code:
(A) Except as provided in subparagraphs (B) and (C), the term “employer” means any person, institution, organization, or other entity that pays salary or wages for work performed or that has control over employment opportunities, including—
(i) a person, institution, organization, or other entity to whom the employer has delegated the performance of employment-related responsibilities;
(ii) the Federal Government;
(iii) a State;
(iv) any successor in interest to a person, institution, organization, or other entity referred to in this subparagraph; and
(v) a person, institution, organization, or other entity that has denied initial employment in violation of section 4311.
(B) In the case of a National Guard technician employed under section 709 of title 32, the term “employer” means the adjutant general of the State in which the technician is employed.
(C) Except as an actual employer of employees, an employee pension benefit plan described in section 3(2) of the Employee Retirement Income Security Act of 1974 (29 U.S.C. 1002 (2)) shall be deemed to be an employer only with respect to the obligation to provide benefits described in section 4318.