The Union manager was angered by a number of decisions made by referee Jorge Gonzalez as his side failed to win against struggling Seattle.
Chief among Hackworth's list of grievances was the lack of a call for what appeared to be a Leo Gonzalez handball late in the game to block a shot inside the box by Conor Casey.
"Having watched some replays in the last 10 minutes, that absolutely blew my mind," said a visibly annoyed Hackworth in his post-match press conference. "Full credit to Seattle, they're a very good team, obviously well-coached, but that should not have ended in a draw in any way, shape, or form. There's a clear penalty at the end of the game, how it's not called is beyond me. And there's so many parts of that game that were mismanaged by the officials, I don't know what to say.
"Look, I'll raise my hand, I'll take the fine, because it has to be said that we can not be in this league and have this level of play, and have officiating be as bad as that."
He also took issue with the red card shown to defender Sheanon Williams following a tepid exchange with Gonzalez that saw both players sent off.
"I don't know how Sheanon gets a red card. It's bizarre."
Asked if he was given an explanation for the card, Hackworth responded, "No. To be fair to Mark Geiger, the fourth, I don't think he knew what was going on either."
Williams was equally perplexed by the sending off.
"We shoved each other, got in each others face and that was it," Williams told reporters after the game. "The referee said we both headbutted each other. That was his explanation.
"I never headbutted him. He never headbutted me. When we were walking off, I talked to him, I asked him if he thought I headbutted him and he said, 'No.' And I said, 'You know, I didn't headbutt you,' and he said, 'Yeah, you’re right.' And that was the end of it.
"I don't know where the ref saw a headbutt. If anything, you want to give us yellows for a shoving match, go for it. But to throw us out of a game, I think was a little bit unfair."
Hackworth's litany of complaints was extensive.
"There were so many calls," he continued. "Michael Farfan gets a yellow card in the first half, he takes a two-hand shove as he's trying to track down the ball, and gets a yellow for it. It's not just one play - forget that we should have had a penalty kick on the clearest handball you can see on video - there's so many little plays in that game and it wasn't against us, necessarily, it was just bizarre.
"It can't happen in this league. Again, I'll get what's coming to me, but I make a bold statement and say that is not allowed, that should not be allowed. And that guy's come here before and done the exact same thing."
The Union coach was also angered by what he felt was insufficient stoppage time when his team held the upper hand.
"I don't want to keep beating a dead horse with this, but I don't know how there's three minutes of injury time. It looked like it took him three minutes for him to decide to give the first red cards alone. There were three goals scored, I think there's six subs. A lot of those little decisions"