Antpool seems to do some mining with a max blocksize of 10kB

The number of transactions waiting to be processed currently is more than 50000. I see that Antpool has created several 9kB blocks in the past few days. Why is Antpool mining blocks with only a few transactions?

I think they have part of their mining facilities running with a max blocksize of 10kB. Are they testing variable max blocksizes? Larger blocks than 1mB will currently not be accepted but smaller blocks are ok.

Or are they preparing for war with Blockstream? If Bitcoin Core will not accept the 2x part of Segwit2x the next fork is coming up. After this next fork more than 90% of the mining capacity will probably support the 2mB branch leaving the 1mB branch with little mining support. That little mining support can also be sabotaged by miners creating blocks with zero or few transactions on the 1mB chain.

By purposely creating small blocks Antpool initially has another advantage. It will cause higher transaction fees and will urge the bitcoin users to support 2x.

The above may suggest that I am on the side of Blockstream but that is not the case. I really don't understand why Blockstream opposes the 2mB blocksize.