The Philly chief believes the Canadian club have been careless with their spending by bringing in Jermain Defoe from Tottenham and Michael Bradley from AS Roma, admitting he was frustrated that TFC owners Maple Leaf Sports & Entertainment (MLSE) had opened up their purse strings.
But Leiweke, CEO of Anschutz Entertainment Group (AEG) - the company that owns TFC - said it was in the rights of the Reds to do as they pleased within the MLS rules.
"I'm sure there are others who are mumbling underneath their breath, but this one was a little bit more than that," Leiweke told the Toronto Sun on Friday regarding the comments from the Union.
"Questioning Bradley is great. Good. Do more of it. One thing I know about Michael is the more people question him ... all they do is get him more committed, more passionate, more aggressive.
"Everyone has an opinion. They're entitled. But 10 times out of 10, I know who I'd take. That doesn't mean the other kid (Edu) isn't a good player. He is. But this is Michael Bradley.
"I hope they keep on him and keep on saying what they're saying. It will only motivate a core piece of our team and the rest of the team around him."
Leiweke added: "Everyone has their own marketplace. On ours, we've sold 17,000 tickets in three weeks. We're going to have a packed stadium every game this year. Our ratings are going to be great. Our merch sells are going to be great.
"In our world, with our fans, with the commitment they've made the last seven years, we owed them this. This is about our business and our relationship with our marketplace. We knew people were going to shoot at us. The shooting has begun.
"I think it's good people are shooting at us. I think it's good when clubs have the kind of roster we're going to have here. We expected this. I think it is a sign of maturity within the league. At the same time, we know what we're doing here. We know where we're headed."
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