As phoolto kindly pointed out, we are a volunteer project which means we do all our work in our free time, without making a single dollar off it.
A project at the size of PG has alot of different facets that require attention, may it be new products on the market, or adding new langagues to our site so folks who do not speak english can improve their privacy as well.
A product as complex as an email provider needs a lot of attention, and I applaud Skiff for working so hard to get listed, I really do.
At this point they are pretty much assured to become listed, they just need to have a little more patience for while we ready things.
Look at notesnook for example, they have had an open forun thread since october last year, and only got added last month.