They have supported ETH on their platform for many years. I think they also mentioned a while back that they hold a fair bit of ETH. Only recently they have turned into "shilling" mode though.
I bet this is one of the reasons behind the recent surge in ETH price, the shilling by the twins and also the fact that ETH futures are launching on CME in the next couple months. That is also probably garnering interest of the investors.
Wasn't aware though that they have a fair share of ETH in their portfolio, I thought they are bitcoin maximalist. But yeah, this is obvious shilling, but it's good though, at least ETH reaches $1k today and maybe we will see some alts follow as well. Market is really taking off starting this year, although bitcoin has it's correction and maybe some are moving to alts, still this overall growth is good for us in the long run.
I would be really surprised to see them without ETH and several other altcoins as well, they were present in Bitcoin before ICO for most top altcoins, and good part of those had airdrop for BTC holders, so at least those are certainly with them, and their position in Bitcoin was good enough for those airdrops to be large
bear in mind that ETH was priced as 1 BTC = 2000 ETH in the ICO, and it outperformed BTC for 50x since induction, so whatever their airdrop was for some altcoins, it is a good position at the moment
nevertheless, as far as I am aware, ETH did not had airdrop for BTC holders