The judge said the BBC ballroom contest isn't all about the dancing as he appeared on spin-off show It Takes Two.
Manrara, who used to be one of the Strictly pros, was expressing her surprise and said it was "shocking".
But Revel Horwood said: "Well, you have to remember, Janette, that it is a popularity contest, as much as..."
Manrara then chimed in to suggest that viewers were the "fifth judge".
Revel Horwood agreed and went on: "So you do have to canvas for votes. Now, how you do that is up to you, but I mean, you know, you do have to win the hearts and minds of the nation as well."
The star said East was a "lovely dancer".
He added: "Let's not forget, other people like Alesha Dixon were in the bottom two for three weeks and then went on to win it. So even if she's in it again, you never know.
"And she went on to judge it!"
East was at the centre of drama this week after it emerged that she was able to restart her dance-off performance after a tumble.
She and her pro partner Vito Coppola were set to perform in the dance-off - where they were up against EastEnders actor James Bye and Amy Dowden - when there was a mishap with a prop and Coppola fell.
They then restarted, which the BBC said was permitted because they had “not begun to dance” before the incident occurred.
In a statement shared with the PA news agency, a BBC spokesperson said the show had been stopped “as a matter of urgency”.
“After an incident with a prop at the beginning of Fleur and Vito’s dance-off performance, the decision was made to halt proceedings to check they were not injured, as a matter of urgency,” the spokesperson said.
“As they had not begun to dance before the incident occurred, it was decided they could start the performance again, once it was confirmed they were fit to do so.”
Watch: Fleur East explains Strictly 'restart' drama