Notwithstanding any other provision of this Act, the eligibility of an annuitant or TRS benefit recipient to participate in the program of health benefits established under Section 6 or 6.5 of this Act is suspended for any period during which he or she is covered under a plan of group health benefits for active teachers due to eligible employment as defined in § 16-150.1 of the Illinois Pension Code. Upon termination of that coverage, eligibility to participate in the program of health benefits established under Section 6 or 6.5 shall be immediately restored, without any interruption or delay in coverage or limitation as to pre-existing medical condition.