You can't just label everything as "doing business" and then regulate it all. If I make something interesting and give everyone in the world the blueprints so they can make one themselves that's not "doing business".
Much as I ardently support FOSS (and similar: open hardware, say) I also think this idea has some use and deserves substantial consideration.
It is difficult to draw the line here, much more difficult than it seems at first, in my personal opinion.
They're just using that as support for why they disagree with the EU rules, since it can be considered "commercial" even if you're making no money, just because someone is losing money.
I don't find the idea useful to anyone but the unscrupulous. I find it very easy to draw the line. If I design something and publish it and people find it useful and put it to use that's clearly not commerce, that's just creativity.
MS give away a browser with their OS, that's still business activity but not directly commerce, IMO.
Now, you say "but I'm not doing that", however the law needs to account for those who would use the freedom to create something and give it away in order to manipulate the market. It happens.
So in my opinion, whilst I absolutely want to ensure FOSS projects can operate, I also want to ensure large companies can't simply release a product as OSS destroy the market and once captured then only update their commercial offerings, for example. So, it needs a bit of thought.