Isn't there a significant difference between "we won't provide you with a free game because we feel you are unlikely (from past experience) to spend the time reviewing it thoroughly or in a timely way" and "we won't provide you with a free copy because we think you are likely to give it a negative review".Simply to have as much sources and opinions as possible. It´s nothing less and nothing more.
My big problem is that they refused to provide the game for review and did that with quite weird reasoning. That simply is more of a proof that developers themselves are not confident with their own game and that´s why they are giving it out to "fans" who are more likely to be actually less negative. We all know fans tend to do that...
I don't actually have a problem with either strategy given that IGN can review it when it is out (and it can be argued that if they do truly feel aggrieved then they will be more likely to review it negatively so Frontier isn't exactly gaming the system).
Either way this is all speculation and it is entirely pointless as there is nothing stopping you from waiting and buying the game after release or not at all when you will have the benefit of all the formal reviews and a thousand youtube videos plus steam reviews, reddit comments etc. etc. etc.
I chose not to buy Jurassic World Evolution because it didn't seem totally my thing and watching gameplay footage convinced me it wasn't for me. Frontier's job (especially their marketing team) is to maximise the sales of Planet Zoo. Even if it turns out you are right, the gameplay has serious flaws and the game isn't good (I played the beta so I'm very confident it will be fun for me and suit my play style) then that would still be their job. There are a number of marketing tools companies use which I consider sneaky, underhand or explicitely unethical but I don't consider 'not providing free copies' to be one of them - if that crosses a line for you then that's fine but frankly I'm a bit surprised you ever buy anything at all!