According to the article, the point of the screeching is because the game is bundled with DRM. A lot of customers hate DRM on principle, many more are wary of performance issues, and given that a lack of DRM has been a major selling point for the GOG platform, an unhappy customer base makes complete sense.
Maybe you don't think the DRM feature will negatively effect your experience...? In that case, great, feel free to leave a positive review of the game. Many other people disagree with you, though, and are leaving negative reviews.
I'm still not seeing why that's an issue, or why that constitutes "review bombing".
Unhappy customers != review bombing.
Customers who dislike a feature that you yourself are not personally bothered by, != review bombing.
It sounds to me more like this is a hamfisted attempt to give preferential treatment to a modern AAA studio, and to turn customer reviews (which are supposed to be neutral, honest reflections of the general state of satisfaction felt by the customer base) into curated advertisement streams (a problem which has plagued Steam for years, and is another reason why many customers choose GOG over its competitors).