De Sousa, a 6-foot-9 sophomore from Angola and a key reserve in Kansas' run to the Final Four last season, has been held out of competition by the Jayhawks since October, when former Adidas consultant T.J. Gassnola testified in federal court that he paid $2,500 to De Sousa's guardian, Fenny Falmagne.
"In my 30-plus years of coaching college basketball, I have never witnessed such a mean-spirited and vindictive punishment against a young man who did nothing wrong," Self said in a statement released shortly after the NCAA announced its ruling. "To take away his opportunity to play college basketball is shameful and a failure of the NCAA.
"Silvio is a tremendous young man who absolutely deserves to be on the court with his teammates in a Jayhawk uniform. This process took way too long to address these issues. We will support Silvio as he considers his options."
In its statement, the NCAA said a student-athlete is responsible for the actions of any third party involved in the recruitment process, regardless of whether the athlete knew of any improprieties or not.
"Membership guidelines state the starting point for these violations is permanent ineligibility, but the NCAA staff recognized mitigation based on the specific circumstances of this case when making its decision," the NCAA said in its ruling on De Sousa's eligibility.
The NCAA said De Sousa, who has not played in any games this season, can appeal the decision to the Division I Student-Athlete Reinstatement Committee, which Kansas athletic director Jeff Long said would happen "immediately."
"This was clearly an unfair and punitive ruling for a young man who had no knowledge of any NCAA violation, nor did Silvio personally benefit from the violation," Long said in a statement. "While we will continue to work with the NCAA on the broader matter, we have an obligation and a desire to advocate for our student-athletes, and will continue to do that for an outstanding young man."
De Sousa's attorney, Scott Tompsett, called the decision "outrageous."
"It should shock the conscience of anyone who believes in fundamental fairness," Tompsett said. "Silvio did absolutely nothing wrong. He was not involved in any wrongdoing by the adults, he did not know about any wrongdoing by the adults, and he did not benefit from any wrongdoing by the adults.
"... Let me be very clear: Silvio never received any illicit money from anyone. The NCAA's decision illustrates the absurdity of how the NCAA enforces its rules: A young man who did nothing wrong has had his life altered in a very negative way through no fault of his own. That is not how we do things in this country."
De Sousa graduated early from IMG Academy in December 2017 and enrolled at Kansas for the spring semester last season. He made his debut Jan. 13, 2018, and appeared in 20 games for the Jayhawks.
Earlier this month, Tompsett demanded the NCAA reinstate his client, saying De Sousa has cooperated fully with the investigation and shouldn't be held responsible for the "illicit" actions of adults.
"Silvio came to the United States from Angola at the age of 15, and he did everything he was supposed to do and was asked to do to become an eligible student-athlete at the University of Kansas," Tompsett said. "Silvio followed the rules. He did nothing wrong."
Gassnola was accused of conspiring with Adidas director of global sports marketing for basketball James Gatto, who was found guilty in October on felony charges of wire fraud and conspiracy to commit wire fraud.
ESPN's Jeff Borzello contributed to this report.