Goals from Dean Morgan either side of Grant's 42nd-minute dismissal for a dangerous tackle on Andrew Wright put the Chairboys in first control.
But after pulling a goal back just before the hour through Richard Brodie, Redshaw struck late to salvage a point for the Shrimps.
"I think it was a good result," said Bentley. "I've got to be honest, up until the sending off it was probably the worst we've played all season.
"I think everything about our play - defending, anticipation, communication, our passing, our willingness, our desire, our clearances - everything was poor about our play.
"If it was 11 versus 11 I think Wycombe would have stuffed us because we weren't at the races.
"But the 10 men played into our hands - we had the advantage, we had the possession, but in Dean Morgan they always have a threat.
"He scored two great goals for them. I've played against him, I've seen him play and it was probably the best performance I've seen from a League Two player this season.
"While he was on the pitch he was always a threat and he proved that with the two goals."