Katamat has taken his case to the High Court at Auckland where he is appealing the finding of the Tribunal, arguing that he should not have been de-registered as a pharmacist.
But lawyer Hayden Wilson - who is representing the health practitioners Professional Conduct Committee - said the Tribunal had no choice but to de-register Katamat.
"The Tribunal heard over and over again that it was someone else's fault,'' Mr Wilson said, referring to Katamat's evidence before the Tribunal.
He said Katamat blamed everyone but himself for the errors but his actions had been "galactically bad.''
Mr Wilson said the amount of Sudomyl that went missing was enough to supply someone for 21 years at 100 tablets a month.
He said every pharmacist knew they had an obligation to control the sale of Sudomyl.
"It is simply not safe to have him in a pharmacy.''
Justice Joe Williams questioned Mr Wilson about the quality of Katamat's lawyer at the Tribunal hearing.
Mr Wilson said it was not the adequacy of Katamat's lawyer which brought about the Tribunal's response but the weight of the evidence against him.
Katamat's new lawyer, Frances Joychild, did not represent him at the Tribunal hearing.
She said Katamat's other lawyer was not experienced and failed to cross-examine key witnesses on important points.
Ms Joychild said the Tribunal and the courts have to take into account that the Ministry of Justice had tightened their provisions for legal aid.
"They have to be aware of the enormous inequality of arms.''
She said the Tribunal's decision had been "punitive'' and other similar cases had not resulted in pharmacists losing their registration.
Ms Joychild said her client's defence had been that he had been set up by an employee who he had accused of stealing from him.
But Justice Joe Williams said the Tribunal concluded Katamat was lying and making up fantasies. "They suspected - without actually saying - that he was selling drugs to a gang.''
Ms Joychild said her client did not face criminal charges and maintains he was not responsible for the missing pills.
Justice Williams has reserved his decision.