It appears Master Exploder is indeed wearing his own custom nodrop blast suit. He just carries a normal one around in his pockets.
More sneaky arena armor shenanigans...
The problem is, in a game with pretty well-establish game-mechanic (UnderRail is one of them), those shenanigans are really NOT that sneaky.
It's blatantly obvious Master Exploder is simply ignoring stat penalties from his suit. And it really rubs me, as a player, the wrong way when I need build up an initiative of X points by using consumables, feats and equipment (all with their own trade-offs), and then an NPC gets his initiative score because he can simply ignore the rules.
It really feels like it would be better to give Master Explode an actual Blast Suit with actual penalties, and then maybe give him an explicit effect of consumable (i.e. root soda for initiative) to offset those.