libttf was one example and because it made its way into 9legacy i inspected it.

Are you implying that a majority of users are using Plan9 in a commercial setting? That seems a bit absurd.
For personal use I think these license issues (if they do even exist) are of no concern. I think you are greatly
exaggerating the possible issue here for your average user.
 
I could tell you about more than two dozens of projects alone at german universities where plan9 was used in medical sensor devices. Calling something absurd which lies beyond your experience gives reason enough to not name any of those projects.

Again, I think in your situation of distributing hardware with plan 9 or whatever, then it makes sense to do whatever your lawyer says.
I think advising against using 9front for every user on these grounds though is misleading at best.

Its not the lawyer who is responsible to avoid copyright issues its the duty of the developer. Not the lawyer gets sued but the one who distributes the system.

Everyone is free to use 9front. But I won't use 9front for a distributed system because I don't have the legal certainty as with plan9. I know who developed plan9 and I know that Nokia owned it before they relicensed it. But I don't this trust in 9front code. And so I wouldn't advise others who make use of plan9 in ways like I do to use 9front.

Do you also remove the Lucida and printer fonts? These were released as part of the original source but have interesting claims as to the ability to redistribute them.
Do you also strip out the parts of ape that include ancient GNU utilities? Are you running your system without a diff and patch?

Of course I removed all fonts from the system. I have my own font library with scaleable vector fonts based on caligraphy. As I stated before I removed any GNU utilities ghostview postscript page and all tools which have clearly GPL licenses are removed. Patch and diff are replaced with BSD licensed versions taken from OpenBSD.

Those are the rules.

And Java runs on a billion devices.

And I can't distribute Java, Linux, commercial operating systems because those can't be distributed as you please their licenses don't allow distribution as the MIT license does.

I'm quite curious as to your definition of "professional" in one where none of the work done by 9front would be seen as beneficial.

I can assure you I respect your fork and the state you reached. Professional use as a distributed operating system needs legal certainty. If you include code from sources and I use your fork than I am the one who is doomed not you because you are no legal entity. I have to make sure that my distributions has no legal issues. The way you answer to such licensing problems makes clear you don't care about them and take the issue lightly.