Saturday's match went ahead at the scheduled time after the WBGT measure showed it was safe to do so, and the FFA also approved a drinks break during each half to help players deal with the heat.
But that wasn't nearly enough to appease Arnold. "Does it need someone to die first? Seriously," Arnold replied when asked about the heat.
"Yeah the wet bulb is saying (it's ok). But at the end of the day, it's roasting hot, and the players can't run.
"They were buggered. "Don't you think the game, in summer, should be played at night?
"If you go and ask those 22 players if they enjoyed the game, I think you'll find 22 players will say, 'I would rather have been at the beach'.
"You may as well throw all tactics out the door. "It's a matter of just hoping the players can just get through the game - with no injuries, without dying, and without making mistakes."
The heat policy also hit the headlines in January when several Glory and Adelaide players reported vomiting, headaches, sunburn, and excessive weight loss in the wake of a scorching-hot game in Perth.
In that match, the kick-off was moved back 30 minutes to 5.30pm, but the temperature was still hovering at around 39 degrees.
Arnold felt there was too much emphasis placed on pleasing the TV broadcaster, rather than focusing on player welfare.
"We've been talking about it for five years. If it's about the spectacle and the performance and the quality, give the players a chance," Arnold said.
"It was one shot each on target (on Saturday). What do you put that down to? "I'm sweating just sitting in the shade."
But A-League chief executive Damien de Bohun hit back at claims the current heat policy was putting players at risk.
"The WBGT thresholds in the A-League are lower than FIFA standards and those used by other sports played in summer, including the Australian Open Tennis, giving our players better protection from heat," de Bohun said.
Arnold also felt Glory's season-low crowd of 6976 was a direct result of the intense heat.
But Glory coach Kenny Lowe didn't have a problem with the conditions, saying Arnold's outburst was probably a deflection tactic after Sydney's lacklustre display.
"Arnie knows what he's doing. He deflects certain things and everyone forgets about the game," Lowe said. "You can't fault the fella. He's as cute as a box of monkeys. He's like the cat with a ball of wool. He just plays with people. So that's the way it goes."