For his actions, Hulkenberg has been given a 10-place grid penalty for next weekend's Italian Grand Prix, as stewards found the incident similar to the 2012 Belgian GP crash that resulted in Romain Grosjean receiving a one race ban.
Hulkenberg missed his braking point and rammed the Spaniard, whose airborne auto skimmed the halo-fitted cockpit of Leclerc's Sauber. "And yeah, the halo was a very good thing to have".
Formula One race director Charlie Whiting said the governing FIA would be contacting Sauber for more information about any damage to the halo.
Leclerc, Alonso and Hulkenberg all retired from the race on lap 1, and Kimi Raikkonen later retired due to issues stemming from a lap-1 incident.
Motorsport governing body FIA made the head protective device mandatory in F1 this year in order to protect drivers from potentially fatal impacts such as loose tires barreling at high speed, other flying debris and - in this case - one auto landing on another.
Liverpool’s Karius set to join Besiktas on loan
Asked after Monday's 2-0 win at Crystal Palace whether Karius was about to seal his move, Klopp insisted he was in the dark. Mignolet has also been linked with Besiktas with Belgium worldwide Mignolet having turned down the chance of a move.
The FIA has been looking at ways to improve cockpit protection and limit the risk of head injuries, after French F1 driver Jules Bianchi - who was a close friend of Leclerc's - died in July 2015 and British IndyCar driver Justin Wilson died a month later.
Mercedes team principal Toto Wolff said at their vehicle launch in February that he wanted to take a chainsaw to the device. "But having saved Charles from harm and injury it makes it all worth it".
The race wasn't without drama, though, after a spectacular first lap crash that saw Fernando Alonso and two other drivers unable to continue.
The German, also hit with three penalty points on his licence by the stewards, crashed into the back of Alonso to send the McLaren vehicle hurtling towards Leclerc. "I think for him, it helped, looking at the replay", remarked the McLaren driver.
"Yet again a very big-time missed braking point", Alonso told BBC Radio Five Live after the crash. "We don't need to prove that it's a good thing to have".