两脚踏中西文化, meaning he is well versed in cultures, namely eastern culture and western culture, implying he is incredibly knowledgeable.
一手写宇宙文章 meaning because he is so knowledgeable and writing Book of Everything (or the Article of Truth) with such an ease, he only uses one hand. Seriously, no one is using both hands writing, but literally, that is how it sounds. He can’t write Bible, can he? He can’t be God. Since Chinese is vague, you can be vague too.
Now, we have my version. It is simply this: Steeped in cultures; Writing the Article of Truth.
LOL, I am kidding.