In fact, there are other laws that require him to withhold the funds based on corruption concerns.
This one is for all the marbles and people are going to go down
There is obvious corruption in Ukraine and Democrats and some Republicans were taking part in the corruption via massive kick backs on misappropriated US foreign aid to Ukraine. These kick backs were laundered through complex transactions with multiple banks in multiple countries.
The guilty are trying to hide this by saying that the investigations into their corruption are political retribution, abuse of power and the evidence was faked by Russian hackers working for Putin
Of course, this does not explain the millions of dollars sent to the personal accounts of the Democrats involved.
The GAO leadership is as dirty as the FBI.