This is an interesting debate and I would like to understand a little more from the community about the issue.
Here are a few things to consider:
Jon Meyer submitted the fantastic Kawai Felt Piano to Pianobook some time ago. He has recently released a commercial version of that library as the Meyer Felt. The original Kawai Felt Piano is basically a “lite” free version of the commercial Meyer Felt. Pianobook has provided Jon with a platform to build an additional income stream from sampling. This was an intentional goal of Pianobook.
Christian Henson submitted the Air Piano to Pianobook. This was an MVP sampling of the piano that became the Spitfire Originals Cinematic Piano. Again, you can see that the Air Piano is a “lite” free version of the commercial Cinematic Piano.
There are also a number of instruments on Pianobook that include only a handful of samples (a few have only one!).
And so it would be interesting to understand what causes this instrument to be objectionable. Is it the word “trial”/”demo” that causes the issue? Is it only having five notes?