Bennett, whose last action at the top level came at the weekend when he sent off Manchester City's Joey Barton at Liverpool, was in trouble with the home crowd and the Bournemouth players for allowing Barnsley's early goal.
Both sets of players halted in their tracks when it looked as if Marc Richards had handled inside the Bournemouth area but the Kent official did not blow his whistle and Stephen McPhail scored with a right-foot shot.
Barnsley, who could have entered the top three if they had won, lost their captain Bobby Hassell in the fifth minute with Paul Reid coming on to replace him.
Bournemouth had plenty of chances to equalise with Marcus Browning shooting over from 10 yards before Nick Colgan dived to his left to push away a fierce shot from Steve Foley.
Bournemouth at last got level after a second half of intense pressure in the 70th minute.
The busy Foley took a corner on the left and new signing Adam Griffiths rose above the Barnsley defence to head home.
Barnsley almost snatched a winner in injury time when Bournemouth goalkeeper Gareth Stewart left his line to meet a centre from Martin Devaney but was beaten to it by substitute Tommy Wright.
Wright watched in agony as his header drifted just wide of an empty net.
Referee Bennett, who was surrounded by angry Bournemouth players after awarding the Barnsley goal, was also busy with his cards.
Bennett booked Richards, Paul Heckingbottom and Brian Howard for fouls and, deep into injury time, he cautioned Bournemouth's makeshift striker Aaron Brown.