That's more the question, considering this:
In a statement on Saturday, Wada said it accepted the three-time Grand Slam champion "did not intend to cheat", that the drug "did not provide any performance-enhancing benefit" and this happened "without his knowledge as the result of negligence of members of his entourage".
The ban seems more a punishment on behalf of his medical staff, and for Wada to retain legitimacy as their rules don't make a lot of sense. I get the hard line on drugs in sport, but the idea of a "drug cheat" doesn't seem to apply here. There were also cultural inferences, which the various Italian agencies need to sort out, as it's a bad look for their leading sportsman to be involved in this.
The worst thing for Sinner is really the stigma that will follow him, at least for some years.
The unfairness here is how he was allowed to compete whilst being investigated and the shorter time it took to reach a decision. But one guy is the #1 player and others are #300, so it shouldn't surprise anyone.