Thanks for suggestions, Adam.
I had not realised that the bug-hunter package can do interactive tests. I used it now and got the same result: the problem is caused by the (cask-initialize) _expression_.
As far as I understand, cask-initialize only collects the directory locations and dependencies of packages as a struct that is then processed later during the emacs start-up. How that can mess up the org cursor movement is a complete mystery to me.
I am using org mode and use-package to maintain, launch and configure my packages. The culprit can not be the tangling process nor the launching of the packages because they happens after cask is initialized (and bug-hunter works on elisp file, only).
I did try emacs with the -q but did not see any difference to -Q.
The one piece of information that I did not include in my posting: My emacs comes from homebrew git HEAD and is installed it with:
brew unlink emacs
brew uninstall emacs
brew install emacs --HEAD --use-git-head --with-cocoa --with-gnutls --with-rsvg --with-imagemagick