Here is an analogy and logic. Jack Ma owns a payment method in China and that is Alipay so why on Earth he will praise and commend a potential competitor to his business?
He can like and compliment the technology but the product itself (bitcoin), he just can't.
We may not know on what's on his mind but that's what I can see and why is it that he's totally not into good words about bitcoin.
Yeah! he is not stupid to like great competitor to his alipay. Bitcoin is a great threat to fiat money, because as what we can see now, bitcoin is technology and technology runs our world and its possible that in the near future bitcoin will become great currency than fiat currency. I think that he is just scared that bitcoin might be more valuable than fiat money in the future.