Hm. I would have to look into MathJax in more detail.
Currently, I am using RMarkdown to write my posts and LaTeX offline. The text from R Markdown would be transferred into the Steemit text window before posting. Any math LaTeX would be done with QuickLaTeX.com.
The following steemit post:
https://steemit.com/steemit/@cryptovest/missing-markdown-functionalities-on-steemit-footnotes-and-mathjax-latex
also discusses this issue. Looks like there was a feature request for mathjax in steemit:
https://github.com/steemit/condenser/issues/7
I wonder how stackexchange dealt with the security issues that led this feature request to be closed?
I wonder how hard it would be to fork the UI:
https://github.com/steemit/condenser
and try implementing this?