Psychic shielding doesnt make you immune to reverse controls that come from characters. Jack has a specific ability that makes him immune to all forms of reverse controls
Onslaugth and bastion are not innune to reverse controls, there is nothing in JG abilities in wich is stated that #psychicshielding champs doesn't get the pasive delirium.
Jack is inmune to reverse controls, that's the reason he is not inflicted with it but he stills inflicted with delirium.
For #psychicshielding to work, it has to be stated on the other champ's abilities. If Jean had "#psychicshielding are immune to it" than it would work