The code being open source
and being made available with a license that is compatible with Mozilla's own MPL2 would be a "hard" requirement for inclusion. While Polaris itself is written in JavaScript (according to the MIT link you've posted) and is expected by its authors to fit into existing browsers, it will have to be seen how well it goes along with the Gecko rendering engine. In essence, it seems to perform a sophisticated caching in addition to conventional dependency checking within a page, thus being able to estimate which additional objects may need to be dynamically included for a specific page based on prior experience with that page.
The other issue is whether or not that's having a chance to be included in SeaMonkey or the Gecko core code as such. KaiRo certainly speaks English (most people in Europe learn it early in school), but is no longer deeply involved in SeaMonkey development. You can open a general thread in the mozilla.dev.apps.seamonkey newsgroup, which can also be done through the
https://lists.mozilla.org/listinfo/dev-apps-seamonkey mailing list. Again, it may be too early to get anybody exited about this, given that the code isn't publicly available for inspection yet.
