For the record, I just committed the following change to Sigil in master:
https://github.com/Sigil-Ebook/Sigil...820bc5b78015cc
So when Sigil 0.9.9 comes out, it will include support for using an environment variable to disable all text cursor blinking inside Codeview in Sigil.
export SIGIL_DISABLE_CURSOR_BLINK=True
I have tested this in my own builds and it seems to work.
If you are a heavy user of Sigil on the Mac and are in desperate need of this feature, please let me know and I will privately post an OSX build for you to use until the next release is made.