The 25-year old forward had a stellar season on loan with the A-League club from Italy's Atalanta, scoring 15 goals in all competitions, which landed him selection in the Socceroos' 30-man preliminary squad for Brazil.
"Am I pleased for him? I couldn't be happier," said Muscat, who took the Victory reins at the end of October when Ange Postecoglou was appointed as Soccderoos boss.
"He took a leap of faith because the general consensus from what's happened over the years is (playing in the A-League) actually hindered their opportunities.
"Now (under Postecoglou) they're in the shop window every week.
"It takes a bit of bottle in a World Cup year to do that but he did that and he's left me immensely proud."
Regarding a possible return to the Victory for Troisi, Muscat added: "He's in a situation where in Italy it's not as easy to get out of your contract.
"What I will say is if I have an opportunity to bring James Troisi back to the football club, I will jump at it."
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