The Mariners were expected to comfortably defeat an undermanned United side still reeling from another bout of controversy, but the match at Skilled Park was a surprising thriller.
After falling behind 1-0 just a few minutes in, Gold Coast impressively returned fire for a deserved 3-1 lead.
But the A-League leaders took advantage when they tired and scored twice in the second half to earn a share of the spoils.
The Gosford club are now six points clear on top, but that buffer could have been greater had they put away their youthful opponents late on when the match was there for the taking.
With defending champions Brisbane Roar quickly finding form and five matches to go yet, a change at the summit of the table is not out of the question.
But Arnold remained satisfied with just the single point and said there was no reason to dwell on an opportunity lost.
"It's a good point, in the end, because it puts us six points clear," he said after the match.
"There's a long way to go yet. Only five games, but a lot can happen. Gold Coast took two points off us so let's hope they can do it to other teams as well.
"Brisbane are in good form again and Perth are in great form. I think there's a lot of twists and turns to go yet."
Arnold suggested that Adam Kwasnik's fourth minute goal may have brought on a feeling of complacency and expectation among the players.
Kwasnik, who put United to the sword in last season's preliminary final, was superb. He had a hand in all three goals, scoring a brace for himself and laying on the pass for Bernie Ibini's 59th minute effort.
But it was the striker's first goal that perhaps inadvertently set Central Coast up for a tougher night at the office than they had anticipated.
"The boys probably thought 'oh yeah, happy days'. Gold Coast came back and gave us a right kick up the backside," he said.
"We showed good character to come back in the second half after being 3-1 down. But I have to say it's the first time I've been really disappointed since I've been with the club of our attitude.
"I thought our attitude was not there tonight."
The former Socceroos coach was effusive in his praise of Gold Coast, who did well to put a week's worth of turmoil behind them and challenge the Mariners.
In the space of just a few short days, the Glitter Strip club was shaken to its foundations after they parted ways with Miron Bleiberg and chairman Clive Palmer began a verbal stoush with the FFA.
But the expansive and exciting performance of the young side under caretaker coach Mike Mulvey provided reason for fans to be optimistic about their future.
"It would have been a crime if Gold Coast didn't get something tonight and I really hope that Mike and the players continue to play that way for the rest of the season," Arnold said.
"When you're living in adversity, you're playing for your livelihood. We all know the situation with players off-contract.
"The young boys are playing for their careers, the senior boys are playing for an extension of their contract. It adds a lot of enthusiasm, especially for kids. I thought they were superb enough."