If you can intentionally convey a message, it can be taken that way, and be used in court that way. A jury would certainly agree that it was meant as a negative review.
On what grounds would you sue? You have neither slandered no libeled the employee since you have said nothing; and proving you said nothing as a way of conveying a negative message would be high bar to cross, especially if it is corporate policy not to say anything beyond verifying dates of employment and possibly other facts such as title and last salary. In any case silence is not knowingly and / or maliciously making a false statement about someone, despite how someone may perceive the silence.
To prove you defamed them they need to show you intentionally made negative statements that damaged their reputation and you knew those statements were false. Not saying anything does not meet that basic standard and a jury would be hard to convince that not saying anything about a person's performance met that standard.
Specifics may be difficult to nail down, but financial harm would be easy enough to prove. Even worse, this doesn't even have the benefit of using truth as an absolute defense.
That's the problem. If you can't nail down specifics to prove a statement (or silence) resulted in you not getting the job then you can't prove any harm. Couple that with the prospective employer is probably only going to say "we found a better candidate and hired them" without giving specifics so they avoid being sued as well and you can see why such a case is hard to win.
As for not being able to use the defense "it was a true statement" since you have made no statement their is no need to prove the truthfulness of what you said or didn't say.