Well why not. If they can do it why can't he. Plus he probably already have a seal similar to Boruto's so it'd make sense that he researched different fuinjutsu techs and learnt a few in the process. Anyway knowing fuinjutsu doesn't make him a pacifist. If anything, my guess is that he tricks Naruto into falling in a trap activating the fuinjutsu and sealing him in the process.So your implying he knows fuuinjutsu on fair ground with minato, tobirama, and obito? That would make Kawaki the very first ever pacifist antagonist... but i strongly doubt he is because well.. look at the village.
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I doubt that Kawaki is string enough to take on Naruto directly. The destruction of the village doesn't prove that he alone was responsible. It could be a group working together and even if he destroy the village alone, Naruto is still much stronger imo. Anyway the point is unless confirmed its nothing but speculation that Naruto is dead no matter how one tries to put it.