That is an awesome poster, and a very.....interesting response given how specific my request was...I'll give you the benefit of the doubt, though.

if you know that service workers are grievously exploited and you choose to have them wait on you while not compensating them, then you are also committing an immoral act...The employer first exploited the worker, then you went in, benefited from their labor for free, directly reducing their income, supporting the business that exploits them while not supporting the worker

So first off, when I walk into a restaurant, I have no way of knowing if the employees are being exploited. If I believe I live in a functioning society with appropriate regulations in place, I have to assume they're not. I have to assume that an employee continuing to work somewhere means they would prefer to keep that job, which means they would prefer the business stay in business, which means they would prefer I spend my money at the establishment. If your argument is that by living in the US I should know that all restaurant workers are exploited and thus I should never eat at one, I respect your opinion, but I disagree.

If that's NOT what you're saying, then how do I know when an employee in front of me is being exploited? Either they should tell me, and I'll leave, or they should quit.

Am I absolved of sin when buying clothing that I know is produced in a sweatshop...

I don't like the choice of the word "sin" here, as that implies some divine being has arbitrarily chosen what "sin" is. I will assume you meant something more akin to "is it ethically conscionable". And I would say, if not buying the clothing means you are unclothed, then yes. Some problems are inherently systemic, and are much larger than an individual will be able to solve before they need to put clothes on their back.

On the other hand, if I'm buying a dress to wear once, and I know it's made by exploited workers, then yeah, no, obviously don't buy the dress.

You could choose to simply not give businesses who don’t fairly compensate their workers your money, but instead, you give them the cost of your dinner and reduce your server’s hourly wage? If people want to reject tipping culture, they need to reject businesses that practice it, not fund them.

Except that, unless the employer opts to break the law, anything between the worker's tips and minimum wage comes out of the employer's pocket. Legally, that's how minimum wage works. I understand that wage theft is a thing, but that exists in many industries, yet you are arguing that uniquely in the restaurant industry, it is the responsibility of the customer to pay for an employer's crimes? That doesn't make any sense.

Your arguments are the equivalent of shifting the blame for climate change onto individuals. Both are systemic problems that can only be solved through regulation, and both have an entire industry built around resisting those regulations. It isn't my fault for not tipping any more than it's my fault for having to drive a gas-powered car. I can't afford an electric car, the infrastructure where I am isn't there yet, the supply of electric cars isn't there yet, all of these are real problems that we are decades behind on solving. In the meantime, I have to get to work.