The short answer is "Yes, the post is missing something". The something in question is some routines to generate code initiated by the changes declared when @tmatrix is output by the CAM.
To generate C or B axis moves you need to set up something that checks if the value you need for your axis of rotation has changed and output the necessary code if it has. However, it isn't that straight forward as the CAM issues @tmatrix twice, before @start_of_job and after @start_of_job and of course if you are using the second one to check if a value has changed the change will not show up using the CHANGE method in GPP because the value changes on the instance before @start_of_job and consequently the change flag sets to FALSE on the call after @start_of_job. Looking back at what I have written it looks more complicated than it is - my advice is if you can structure your NC program to call the pallet rotation before the start of job and therefore sometime the tool change, go for it otherwise there lies ahead some significant post tweaking.
Something to be aware of is when you rotate the part what happens to your MAC and hence your G54 etc. If the part is positioned on the centre of rotation when it is in the machine every is easy but if it is located some distance away from the axis of rotation, say on a tombstone fixture in the case of a HMC, then you have decisions to make about how you handle that.