While there are still a few obstacles to be dealt with between now and then (Aster/Eclipse and Taka, which can be on the challenging side if unprepared), I'm looking forward to that Garchomp battle as well - it's one of my favorite things to see people react to when they're playing the game blind. But, while I still hold some hope that maybe nobody has spoiled it for him yet, the people in the comments section really seem to love to blab about it. If he got spoiled on the Victoria fight this time, it seems almost impossible that he didn't see comments talking about the Solaris fight. Which would really suck, but oh well - that's comments sections for ya.
At any rate, the Garchomp fight will probably go one of two ways - he could either cancel the Nuzlocke right then and there (which, in all honesty, would probably just be because he isn't enjoying it much anymore anyway) or he'll make a clause and keep pushing. I kinda hope it's the latter, since I really want to see how he fares against Aya (it's between her, Shelly, and Titania as fights that gave me the roughest time my first time playing), but we'll see how things unfold from here. While he makes his share of questionable decisions at times, I still hope that he has fun with the game, and I hope that he continues with it once the Nuzlocke ends, whenever that may be.