Even if they didn't know CC wasn't suitable for software, everyone knows that non-commercial isn't Open Source.

I didn't dig into the software, but I wonder if the licenses for the dependencies allow this either, eg if any are GPL or similar.

This is wrong. CC is perfectly fine for software in some cases, such as here.

Ok, CC is not tailored specifically for software, thus the general advice "you should use something else" but I do not see why CC would not be suitable here to achieve OP's goals.

Can someone explain?

    Unlike software-specific licenses, CC licenses do 
    not contain specific terms about the distribution 
    of source code, which is often important to ensuring 
    the free reuse and modifiability of software. 
    Many software licenses also address patent rights, 
    which are important to software but may not be 
    applicable to other copyrightable works. Additionally,
    our licenses are currently not compatible with the 
    major software licenses, so it would be difficult to 
    integrate CC-licensed work with other free software. 
    Existing software licenses were designed specifically
    for use with software and offer a similar set of 
    rights to the Creative Commons licenses.

The CC licenses do an amazing job when it comes to artistic work such as books, movies, music, etc. but you don't have the same issues there, and that's why even CC says that they don't recommend using them for software.

And it is open source.

Probably not OSI-open source or FSF-open source but it is open source, period.

Why should we restrict the meaning of Opel Source, a societal mouvement since decades, to a list of criteria that FSF or OSI decided?

Open source is not a trade mark by FSF or OSI.

OP did not say it is free/libre software, but just open source, which it is.

We don't need "source available", just open source is correct.

PS: can you define the open source body in your previous comment?

I can define Open Source easily, using the OSI definition.

There is not a trademark for Open Source because they failed to secure the trademark, but we have decades of use for the term meaning something specific.