This struck me as almost a perfect example for good content on a company blog (outside of the required press-release style posts). Ties into their software, light-hearted, polished and well put together.
One thing often missing from these types of solutions (this one included) is that it's extremely easy to generalize them beyond the 9x9 case.
Mixed-integer and 0-1 integer programming problems are NP-complete in the general case. You might as well use the backtracking approach which in my opinion is much more elegant.
I actually just wrote an add-on for Google Sheets (It allows you to run neural networks in a spreadsheet). While I resented being forced to use Google's Apps Script Editor, I was impressed with the quality of the documentation and reference materials. They've done a pretty good job.