Since Snorri himself was a Christian, and his works are some of the most popular sources for Norse Mythology, is he to blame for the modern "Christianized" interpretation of Norse gods and beliefs?
Short answer: probably yes. He's our primary source for a lot of myths, which makes it hard to say our interpretations are accurate to what was believed a thousand plus years ago because we don't have anything to compare it to. He was Christian, and likely fudged/altered much of his recording of the myths to make them fit into the Christian worldview.(such as demonizing Loki or at least making him fit more the Christian role of an evil/demonic figure rather than the classic trickster figure he's more likely to be, the whole Ragnarok myth isn't actually recorded elsewhere, the idea of Heimdall becoming a Christ-like figure after Ragnarok, a man and a woman repopulating the world after the end of the world... there's a Lot.)
However, it's not all his fault, probably. He was writing several hundred years after Christianity became a major force in Iceland, so many of the myths may have changed already by the time Snorri was born. And the myths we know now are Norse myths are primarily just from Iceland, which had a lot more integration with Christianity than a lot of other Scandinavian countries, iirc. There are a lot of factors, but it's largely due to Snorri. It's a lot like basing all your knowledge of current world religions off a book aimed at teenagers on the subject.