Soward, 28, will sit out Friday’s Super League clash at Widnes with a back injury, having made three appearances for the Broncos since joining from St George-Illawarra on a short-term deal.
Rea said: “We genuinely have some bad knocks. We’re not resting anybody this week.
“He’s done a real lot of travelling and he’s stiffened up during the week.
“Given his workload and what he’s been asked to come in and do, his back was untrainable today so there was no way, given the number of miles he’s travelled, that he could compete in this game safely.”
Soward scored a try, two goals and a drop goal in the 29-10 quarter-final victory over Sheffield last Friday.