Yet such is the speed with which things can happen in football these days that that is, factually speaking, precisely what has and is about to happen. However, before Shane Warne and company dispatch a lynching party in the direction of the Twin Towers to deal with such traitorous behaviour, one should quickly point out that the Crystal Palace defender, who is set to play in today's First Division play-off final against Sheffield United, has not gone so far as to switch his allegiance to the Old Country, even if it was his birthplace.
Last month Muscat won his 10th cap for Australia and his first under Venables when the new coach to the Socceroos brought him on in the second half of an international in Budapest. Muscat responded by giving his side the lead before setting up the third goal in a 3-1 win over Hungary - another example of how rapidly the face of the game is changing these days.
The Melbourne-bred Muscat captained Australia in the Atlanta Olympics last summer and is proud of his nationality: "I'm very Australian," he insists. But his chosen profession has necessitated that he return to England 22 years after he and his family left Crawley for Down Under when he was just one year old.
Ironically, he might easily have been playing for the opposition today, having been initially invited over for a trial by Dave Bassett when he was manager of Sheffield United. It was at the time of the Bramall Lane club's protracted takeover and the money was not there to buy him.
"I'd agreed a deal with him and everything," Bassett said. "He was a player I liked, but Howard Kendall decided he didn't want to take him on. Then I got him down to Ron Atkinson at Coventry and they didn't want him either. But I signed him straight away when I took over at Palace."
So highly did Bassett rate the player that he selected him for the opening game of the season at Birmingham, even though he had only been back in the country seven days. Muscat remembers his debut only too well: his mistake led to the only goal of a game which Palace had dominated. "I went home that night thinking: 'I've arrived'," Muscat said.
However, he had impressed Bassett with his character. "Considering that he dropped that ricket just 20 minutes into his debut, it could easily have done him in mentally. But it didn't, and he's gone from strength to strength," Bassett said. "He's a tough cookie, very athletic and a good footballer. I was surprised other clubs didn't take him."
Venables' predecessor at the Australian FA, Eddie Thomson, once said of Muscat that "if it meant winning he'll even kick his grandmother". Muscat said he is eager to have words with Thompson to see if he really did make that comment. Apparently, what he said was grandfather, not grandmother.
Seriously, though, he has missed only one match through suspension and, since he is the sort who does not easily pick up injuries either, it has meant that he has been readily available to first Bassett and then his successor, Steve Coppell, this season. Only Andy Roberts has played more games, which is good news for the South Melbourne club. Bassett paid them pounds 75,000 down, rising to pounds 200,000 after 100 appearances. Muscat is already well on the way to that figure with 49 league and cup games this season.
That is significantly more than Muscat's fellow Australian international, Carl Veart, who, following his own move from Sheffield United, has struggled to settle as well as Muscat. Paradoxically, Veart and his wife have gone out of their way to ensure that their friend has, and he says he is indebted to them for that. Immediately after today's game Muscat flies home to Australia to marry a woman from Melbourne before returning to England to set up home.
The exodus of Australia's best players has tended to stunt the growth of the game back home, but Muscat believes that the appointment of Venables has considerably raised its profile.
"From what I've seen of him in that one game against Hungary, his knowledge of football is different class," Muscat said. "And the way in which he passes it on to players is incredible."
Muscat is hoping to glean more from England's former coach during the summer, when Australia's World Cup qualifying programme picks up pace. If, as expected, they are successful in the Oceania group they will then have to play off against the best of the Asian losers, who happen to have Muscat's utmost respect.
It has not escaped his attention, however, that Australia could be playing in the finals in France next summer while the old country twiddle their thumbs at home. What a rich irony that would be, but a thought no more preposterous than that one of a year ago which became a reality for Muscat.