Just like President Obama tried to veto a bill that would allow families of 9/11 victims to sue saudi arabia?*cough*Saudi Arabia's Crown Prince Mohammed bin Salman*/cough*
If it suits Trump's interest, he will defend a murderer the same way he defends just about everything else he does, by lying a lot and pleading ignorance.
https://www.reuters.com/article/us-usa-sept11-saudi-idUSKCN11Y2D1