For the purpose of the law, appropriate means
Direct deposit means he acquired control over the money.
By your definitions, he was thief prior to spending the money because
a) he had control of it (direct deposit = appropriated per your opinion)
b) it was given without the "owner's effective consent" (per your opinion)
Had he died upon seeing his deposit, he would still be a thief per your interpretation. (!)
But you also argue he is a thief for not returning the money but there is little yet to suggest he has that obligation. No civil judgement and the direct deposit agreement sited only gives permission for one party to withdrawal incorrect amounts. It doesn't force the other party to return incorrect amounts.
So, to attempt being reasonable, the direct deposit could not be the approriation. Withdrawing the money could be and that does better demonstrate that "
mens rea" thing internet lawyers like to talk about. There was a case where I guy with cancer left a job, stayed on payroll for a year, said nothing, did nothing. He returned the money upon being asked and things didn't "get ugly". There was no suggestion he was a thief and I'm not aware of attempts to prosecute him. In fact, all the people that have not been prosecuted for this, ought to make defense a piece of cake. Is the DA going to say, 'yeah but this guy is sort of ethnic looking, got a DUI, and drove a fork truck'???
There has to be some clear point in the timeline at which he broke the law in question.
1) When getting the money is out of the question - he did NOTHING to acquire it!
2) When withdraing money is a possibility (note not "the money", but "money" - the shit is fungible)
3) When not supplying a requested amount of money is a possibility ("a requested amount", not the whole amount as we know some of it was intended to be paid - which dollars are innocent and which are guilty, we'll never know).
The odd thing about #3 is that if you owe me $100 due to our civil interactions, I can't call you a thief for not paying right away. I can certainly think of you as one but the process at that point is civil or debt collection - not criminal. We have had customers owe us tens of thousands of dollars. Not a single one has ever been charged with a crime because they filed for bankruptcy. Even if they were scum - they aren't - we can't have them treated like thiefs. I'm sure the cops would point us towards a collection agency or other civil solution. OWING MONEY IS NOT A CRIME!
The odd thing about #2 is that it is his money, at the time, and there has been no notification of the error. Had he been notified
and then he spent or withdrew the money, maybe you would have something. He withdrew the money and only later did the employer want it back when they changed their mind about how much they wanted to pay him.
When in the timeline is he a thief? It cannot be when money was appropriated (direct deposited). It cannot be when money was withdrawn or spent unless we admit the naked truth that bank accounts aren't really our money (lol - besides company didn't yet want the money back). It cannot be when money wasn't returned because that will be a civil action or some other law they didn't reference.