Your initial response seemed to be primarily consequential...but your follow up seems deontological. If you argue that taxes are never justified...then there's absolutely no need to offer any consequentialist argument. It's like debating whether following the 10 commandments has positive consequences. A commandment is a commandment...the consequences are irrelevant.
People justify taxes using consequentialist arguments...so I could care less about deontological arguments. My goal is to help people understand how the invisible hand works...which has absolutely nothing to do with deontological arguments. So you're really in the wrong forum category if you want to debate morality. Economics is completely value neutral.
Here's how I see the problem. The large majority of people believe the market fails in at least a few areas. The only exceptions are anarcho-capitalists. They believe the market can supply everything. In order to discern the extent of market failure...I believe we should simply allow taxpayers to directly allocate their taxes. Their tax allocation decisions would reveal supply shortages in the private sector. For example...if people choose to give their taxes to the dept of education...then we would be able to discern how much of an education shortage there was in the private sector. Because if there were adequate levels of education available in the private sector...then why would taxpayers choose to spend any of their taxes on public education?