I think the fee of ETH will cost them a lot too with each participant of about 50cents of fee.
For the last transactions it was $2.36 per transaction, see e.g. this transaction:
https://etherscan.io/tx/0x7733fea49be9bfda5b96fcc5a18184337ce7b8b61538ef7aa07be81e9aa2dbb3But looks like it is still getting slower: 20 transaction for last 3 hours. At this speed it won't be finished even until the end of this year.
Does anyone know the details of Ethereum transactions? Could they add more than one receiver in one transaction? Don't know, at the moment it really looks like some poor soul is using a wallet and manually transferring all the tokens, sometimes an hour pause when he has lunch

Hope them, the team will come out with a good solution instead of doing it manually. Perhaps, they can split the distribution to around 100 people to speed up the progress 100 times? Just a thought.