Unfortunately all the jailbreaks in use today are closed source and obfuscated to some extent :(

The moral issues with open source weapons--which is what jailbreaks should and need be considered--are myriad, as you empower increasingly weak and diverse adversaries the easier you make it to retool for different purposes. I appreciate that opinions on this matter differ; but I've struggled with these issues for well over a decade, and I still believe that "open sourcing" (which is an action that lies along a continuum) a jailbreak tool is are not ethical (and so am somewhat relieved to hear that this one isn't truly open source; though I fear that, given the authors, the parts kept closed source may be serving the wrong goal).

>Unfortunately all the jailbreaks in use today are closed source and obfuscated to some extent

In that case why we call it a Jail-Break? I would rather call it a Jail-Switch/Choice ...

It's another Jail if I still don't have a full control.

You should have full control of the resulting system: the concept of having control is unrelated to knowing how you got said control.

In case you indeed got full control. How do you know?May be someone else got full control and you got only part of control or illusion of full control with backdoor for them.

Because the creators realise that Apple is actively fighting them.

No, not at all. Apple usually fixes bugs before a jailbreak comes out for them.

The linked jailbreak claims to be fully open source, although I haven't bothered verifying that.

It's not; there's more than a few zipped up binaries in that repo.