We have clear scientific consensus on the fact that vaccines reduce the negative effects of getting COVID, and reduce the likelihood of getting COVID in the first place.
So declaring that vaccine mandates won't affect populations 'because you can still get it' is effectively twisting the truth. Or at least applying some really bad logic.
The link you provided is unfortunately not helpful. Again, there is overwhelming evidence that actions taken by governments were successful in most ways in preventing spread during the pre-vaccination era. Huge spike is case rates were immediately neutralized by lockdowns etc.. The moral and legal case is ambiguous, but not the overall effect of the policies was clear. In my area, we had two huge spikes, after which there were lock-downs declared, and immediately the case rates dropped dramatically. I'm wary of the civil issues, but the results were clear.
The article provides no evidence that vaccines don't work, other than to indicate that protections against Delta variants is weaker, which we already knew.
This statement: "The principle defence against a respiratory virus actually takes place in the mucosal membranes of the respiratory tract, and the high proportion of those with some degree of natural immunity fight off SARS-CoV-2 there, preventing it replicating significantly in the bloodstream. Therefore, it is not actually surprising that a vaccine which works mainly in the circulatory system has little effect on stopping what starts as a respiratory infection. If that is the case, it is illogical to expect any reduction in transmission."
Is hugely speculative, not Scientific.
The author of this piece failed to play their own devil's advocate because there's tons of data to debunk most of what he is trying to say, in a nutshell, the author is cherry picking.