Try paint remover on the glue that is holding that stuff on. I have seen that that fuzzy stuff before, but I can't remember where -- it's what the factory filters were made out of on either XT500s or some year XS650. But, it's not supposed to be where yours is. That is definitely the work of a PO. Maybe to support the filter as you suggest -- your guess is as good as mine. Those red paper filters in your pics are replacements. They should be a decent fit without the fuzzy stuff.