Yeah, that's really the nut of the problem, isn't it. Short of finding a lawyer qualified to speak to these issues -- which I can't afford -- my only other option is to simply avoid the GPL. Which sucks.
I don't really like that solution either (it kind of defeats the purpose of having a legally binding license), but it's the current solution silently adopted by a lot of people interoperating with GPLed code using any of the techniques described in your article.
In a world where technology advances an order of magnitude faster than legal theory, it's just going to be a fact of life for a long time that there are many technological questions that have no clearcut legal answers.
I think that's a hope that I, jacob and many others are not willing to sign up to.
Check out this article on Groklaw ("The GPL is a License, Not a Contract, Which is Why the Sky Isn't Falling") for more: http://www.groklaw.net/article.php?story=20031214210634851
I've found it helpful to clear up that misconception, point to past infractions / events, and try to humanize the free software community. In most cases, there isn't a litigious company lurking in the shadows, and a show of good faith will go a long way. It's also quite useful to direct attention to high profile products that are safely using and modifying GPL'd code, like the Kindle.
The problem is not just the case where a company does get hit with a lawsuit if it should violate the GPL as it might nebulously apply to myriad situations.
It is the very possibility of such an event that will scare away those who might otherwise fund your company or who might otherwise acquire it.
I know. I deal with funding rounds and M&A very frequently in real-world situations. Believe me, if the GPL pops up in due diligence, general panic ensues unless it involves only some incidental use that can be worked around or it involves a very clear-cut case of how the license applies.
As an entrepreneur, you can lose and lose badly in such situations even where no lawsuit is ever filed.
And talk with the copyright holder of the software you're using! It's a good idea in any case, and will probably go a long ways towards getting an idea of what they're comfortable with, and what they think their rights are under that license.
-- Here's this GPL licensed code. Go ahead and use it, and so long as you keep with the "spirit" of open source, I won't bother suing you. When I die, however, and the executors of my estate notice that they now control copyright on this GPL'd code that you might have used to grow your multi-billion dollar company...all bets are off.
...is better than:
-- Here's this BSD licensed code. I'm not going to require anything of you to use it, but I expect you to keep with the "spirit" of open source and contribute back to the community. If you don't I have no legal means to force your hand, but if you die and haven't contributed back, your fork dies with you.
And consider that in the worst case, you're no worse off than if you encountered a proprietary-licensed library that was too expensive for you to use.
Actually SAS licenses are simple - you are allowed to use the product to send SAS all your money, any other use is probably forbidden.