The truth is somewhere in the middle. Some of the VOCs from the copier will get trapped in the bag of charcoal. Just by virtue of it being there.

But this is absolutely not how effective filtration works. Filters are classified in terms of the media used, and the percent of a given particle size they're expected to block from the air that passes through the filter. Since we have no idea how much air is passing through the bags of charcoal (some percentage only slightly above zero) we can say that the air is effectively unfiltered.