http://akimmigration.com/syriaTPS-USCIS-FAQ.pdf

See the last question answer from the USCIS document in the above link.

Answer: A TPS beneficiary is granted an “open market employment” EAD. This means that the EAD gives him or her unrestricted access to employment in the United States. The fact that an H-1B nonimmigrant is granted this type of an EAD does not cause the alien to violate his or her nonimmigrant status, if he or she continues to act in accordance with the requirements of his or her approved H-1B nonimmigrant petition. However, the nonimmigrant will violate his or her H-1B status if s/he uses the EAD to engage in employment for a separate employer and leaves the employer listed on the approved I-129 petition.