Powershell: Returning data tables without rows in functions
I think your problem will be solved by simply using the unary comma operator in front of the table you're returning:
return ,$tablePowershell does some interesting automatic unrolling of collections that implement IEnumerable. The comma operator will wrap your table in a single-object array, so when it gets automatically unrolled it will return back to the table. I don't know of a way to force Powershell to not do this.
Here is a reference to the operators.