I don't think so. You've got three factions here so you have to make sure you have the proper loyalty symbols. So there is a hidden cost there.
Return to Glory does look like it can return Peasant Militia indefinately.
Grudge Thrower cost 1 resource each time its used so that is 1 resource each time you sac the Peasant Militia.
Burying the Grudge is a 1 time effect. So best case scenario is you use all your resrouces to sac Peasant Militias and buff another unit. Then play Bury the Grudge and gain all your resrouces back (1 for each Peasant Militia that entered the discard pile)... but I'm not sure it works that way. I think the Peasant Militia card that is saced over and over again is the same unit... in which case it would only get you 1 resources... anyone have a clarification on that. What its effect does not do is stay in play the rest of the turn.
If the idea is to buff the same Peasant Militia with its own sacrifices that won't work as a unit coming into play loses all benefits it had prior to entering the discard pile. Its like a few unit is being played.
Those are my thoughts on the combo.