This verse sets out the trap laid by the Pharisees, and it begs the question as to whether the man in the first verse had a physical ailment or was miming being maimed. The Pharisees were not expecting a healing miracle but a taboo activity, and so setting someone up as if they had an ailment that could definitely be ‘cured’ was all they needed to do.
In any case, this verse makes clear that the Pharisees are not acting in good faith, but have deliberately contrived this situation.