Any surge suppressor should have the U-ground connections from the individual receptacles bussed straight through to the wall plug's U-ground pin. Some of the cheap surge suppressors have flimsy wiring and poor contact grip, and that might cause a problem getting the TMCC/Legacy signal into the house wiring.
Any cross coupling of the TMCC signal from the safety ground wire to the hot or neutral by capacitance of the suppressor devices shouldn't harm the TMCC signal since it will be coupled to those lines anyway by wiring capacitance, load resistances and the neutral-to-earth-ground bond at the panel.
