Let's look at what he didn't do:

During that IMPEACHABLE PHONE CALL, President Trump asked him if he had any information on the Biden's suspicious activities in his country.  You know, I know, and the country knows Zelensky was/is fully informed on every activity the Biden's undertook over there.  

He could have said, "Mr. President, I will share with you all I know in a more secure setting." 

But he didn't. 

He saw how Ukraine played the Biden's like a fiddle and he wanted to continue the relationship.

He could have saved Trump and the country from a 2nd impeachment by simply stating Trump's inquiry was not only appropriate but also long overdue. 

But doing so would have contributed to Trump's re-election.  That was not what the Bureaucracy wanted and Zelensky got the memo. 

When UBS was asked what prompted their need for an additional building, they replied... "Stop the aid to Ukraine and we'll revisit our growth projections."