The article doesn’t give any details to explain why these artifacts indicate continued “paganism” or identify Thetford as a “cult centre.” The only fact mentioned is that the items seem to have stylistic elements that are similar to those of continental European artifacts from a considerable distance. They don’t explain why that is relevant to the “paganism” thesis, rather than simply indicative of long-distance trade in elite artifacts, duh.
Perhaps paganism is suspected because of the complete lack of any religious artifacts, like crosses or religious medals. On the other hand if these pieces were secreted for security purposes and existing danger, perhaps the people would have kept their religious artifacts, whether pagan or Christian, on their persons to ensure safety by God’s aid.