It sounds like a case of "when all you have is a hammer, everything looks like a nail": going for the bad solution that they know, rather than doing a quick search online to see if there are any better options out there. Or it was a stack decision forced onto the developers by management.
For example, Qt Quick is an excellent, mature framework designed for doing secure cross-platform JavaScript desktop apps. Maybe Electron can do it properly too, without the local server, for all I know.