Great sketching app! But unrelated to Muse, which is a thinking workspace focused on text, PDFs, links, and images. The ink annotations and ability to sketch are a minor feature.
Plus it supports images, and drag-n-dropping them directly from other apps in a iPad split mode makes it a joy to use often.
For some, the best "tool for thought" is something that tries to replace paper as directly as it can, because writing/drawing on paper is how some people think best.
So I don't think it's quite fair to say this is unrelated. Perhaps the feature sets are different, but the underlying goal of the end user might not be.
Guess my point here is that Muse is not an attempt to translate paper into the computer, other than some superficial elements like using a stylus to ink. IMO software and computers can go so much further than that.