At bare minimum, I distinctly remember Vince Vinny Vini ignoring the Challenge (admittedly to his detriment).
As far as grabbing him: Out of combat, a skill check to grab would 100% stop him (or at bare minimum slow him down if it were Night Cap). The in combat power Grapple doesn't officially stop someone from moving despite the flavoring since combat doesn't acknowledge range. What I will allow for this one time is Beathra using the Grapple power with a DC 25 Presence roll added. If Beathra hits the DC, Master SAVAGE will stop in place for 1 turn. Of note, Beathra does have a high Presence and still has access to a Hero Point.