Well that isn't true. The clubs have to release players for international windows. FIFA rules. Clubs do not have discretion.
Yes the players were released for the window game/games, but key players minutes will be managed according to their individual needs and situation.
The reason is that everyone (everyone who gets paid to watch football from the sidelines) understands that nothing commercially significant is riding on a result of a couple of friendlies (which is what "Soccer Ashes" are). These ain't WC qualifiers against top grade teams.
I clearly remember a very feisty Australia-New Zealand game shortly before Australia was to go off to the World Cup (apology but I do not remember which one). Their team management was rightly livid at the high-level physicality from the AWs; they were concerned some of the Australian players' could have gotten injured in that friendly and would at worst miss the WC tournament or even just as much affect their playing form in the WC if they had to recover.
What we are talking about here regarding managing Thomas or Woods or Boxall minutes comes from exactly the same place of concern regarding bigger objectives, both short term and long term, for the players.