I think it is fine to talk about startups and even criticise them when you have something constructive to say. In the case of Peach I had literally nothing to add that was constructive so I kept my opinion of it to myself.

Building an accurate assessment of whether it's going to succeed is one of the most productive things that can be said about a startup.

Such assessments are notoriously inaccurate, except in the trivial sense that we all know most startups won't succeed.