Yes, that's an issue. Yes, he should put them on the shelves like he's paid to do (or if that's not his job, then let it be done by the person whose job it is), then come back on his own time and buy them like everyone else (or miss them like everyone else, if someone not working got there first).
And how do you know he put them on lay-by? That linked post says nothing of going on lay-by, just that he put them on hold for himself (with a picture of them loose out the back in the stock-room). I'm willing to guess that someone who freely calls what he does abusing his role and scummy has probably just shoved them somewhere that nobody else can get at them.