(a) This subchapter does not apply to public construction contracts executed before July 22, 2015.
(b) This subchapter does not:
(1) Prohibit an employer or other party from entering into an agreement or engaging in another activity protected by the National Labor Relations Act, 29 U.S.C. §§ 151 — 169;
(2) Interfere with labor relations of parties that are left unregulated under the National Labor Relations Act, 29 U.S.C. §§ 151 — 169; or
(3) Prohibit a public agency from awarding a public contract, grant, tax abatement, or tax credit to a private owner, bidder, contractor, or subcontractor who enters into or who is a party to an agreement with a collective bargaining organization if:
(A) Being or becoming a party or adhering to an agreement with a collective bargaining organization is not a condition for the award of the public contract, grant, tax abatement, or tax credit; and
(B) The public agency does not discriminate against a private owner, bidder, contractor, or subcontractor in the awarding of the public contract, grant, tax abatement, or tax credit based on the status of the private owner, bidder, contractor, or subcontractor as being or becoming, or the willingness or refusal of the private owner, bidder, contractor, or subcontractor to become, a party to an agreement with a collective bargaining organization.