From doing some digging around, the US decision to not send them was officially because they did not want to cause an ‘escalation’ when the manufacturer of the drones said it was more to do with one of these drones being downed and then the Russians being able to reverse engineer it.
Having the best air defense systems in the world shooting down one of your top bad ass drones being utilized by inept, untrained Ukrainian hands probably would not look good for international sales either.......
A definite possibility.