The question is not so much
"Is he entitled to apply?"
Basically, he is.
The actual question is,
"So, if he does apply, does he have reasonable prospects of success?"
(ie will he actually get a visa?)
We are limited to generalities on here, so it's hard to provide meaningful detail in an answer.
His chances depend on (among other things) the exact charge (no, don't tell us),
and the penalty that could be imposed if he is ever convicted.
I certainly encourage you/ him to be completely honest on his application.
Overall, having any criminal matter in the mix is... less favourable.
Concealing your back story from Australian authorities is worse.
Among other things, he would need to satisfy the Immigration Department that he is
not in fact simply fleeing the jurisdiction where he is being prosecuted.
He may also have to consider the question of being able to leave America during the suspension period.
That is a separate question to whether or not he would be allowed to enter Australia.
Are you already sure that the US Government (at any level) has no problem with him leaving the country?
One last thing - I encourage you to engage a WA lawyer who is also a Registered Migration Agent.
If only because it's important to remember that
it's a really bad idea to make big decisions
based on what some guy says on the internet.
Good luck.