The payment rate may be low but if the price of Bitcoin increases then you will have an increase in payout so far it is one of the few campaigns that payout with satoshis, and this campaign is good for those who want to hold Bitcoin for more profit in the future, there are a lot of applicants because there are more active campaigners now than before
All campaigns are paying in satoshis, but most would have rates defined in USD. But it doesn't really matter, as those who want to spend their earnings would convert btc to fiat straight away anyway, and those who want to hold btc could just buy them even if they got paid in fiat.
Applying for a spot in a low-paying campaign just for the hopes of btc going up in the future makes completely no sense. No one, who has a better option would go for it. And if the btc goes sharply north, I'm sure rates would get adjusted pretty quickly.
But there's no harm for a business to offer low payouts and see how it goes. If they fail to attract quality (or any) posters, they could be slowly improving their offer until they get the desired result.
So let's see how that pans out.