Yes, there is, Mr. Harris.
I have perhaps a number of comments I could make in response to your question, but to address your immediate question, the way these exemptions are framed in the clause is both on the basis of the objective gravity of the offence, which is determined by the maximum punishment that Parliament prescribes for an offence when it creates the offence, and the subject of gravity, which relates to what's actually given in a particular case.
To answer your immediate question, when one looks at what Parliament has prescribed in terms of the objective gravity of the offence for section 83, it's punishable by life imprisonment; Parliament has said, in creating that offence, that this is among the most serious offences known to law. Therefore, given that objective gravity, Mr. Harris, it would seem not to be appropriate to include it in that list.