Grant scored a stunning 66th minute goal to cancel out Jay O'Shea's opener and earn Dale a point on Keith Hill's first game back at Spotland since his return as manager.
But he blotted his copybook five minutes from time when he was dismissed for a lunge at Sam Togwell.
"We probably saw the Jekyll and Hyde of Bobby," said Hill.
"His goal was his performance. He was a constant threat and he's difficult to stop when he coming on the inside onto his left foot from a wide position.
"He was playing very responsibly but you can't legislate for the challenge he made and it was obvious it was going to be a red card."
It was the one downside for Hill on his second home debut as manager, and he was pleased with the response from his players after falling behind to O'Shea's neat 55th-minute finish.
"I enjoyed the occasion immensely," he said.
"And I thought a draw was a fair result.
"I am learning about this league again, learning about opponents and it's only the second game we have had since I came back.
"I have learned a lot about the lads in training, but you learn more about them in real action and today was real action. It was a great test for the players when we went one nil down. I wanted a bounce back and a response from the players and I got one."