I'm glad you had satisfactory results from your meeting. I believe that the attitude and demeanor of the pathologist tells you a lot about how they conduct their business. It sounds as though this doctor at least took the time to address the issues in relation to cause of death. That's important to you and hopefully brings you some comfort.
However, I don't believe the toxicology results can be given much weight in the matter. As I recall, there was a single subclavian blood sample drawn at an unknown (to me) time. (If there were additional samples drawn, please let me know). Here let me refer to a couple of doctors far more experienced and internationally recognized specialists:
"There is substantial published evidence to show that for most drugs... there are important differences in their concentration in blood according to the time of specimen collection after death, choice of sampling site, method of sampling and volume of blood collected (Pounder and Jones 1990; Pounder 1993). It is common to observe tenfold differences in the concentration of certain drugs.... in post-mortem blood taken from different sites."
Clear your head of all ideas of in vivo toxicological analyses. Postmortem toxicology is completely different. Postmortem there is no even predictable distribution such as occurs through metabolism/circulation in life. Rather the processes of postmortem redistribution (PMR) take over and that is dependent on numerous factors, two of which are the pharmacokinetic properties of the drug and the elapsed time between sampling and time of death. The results obtained postmortem are not a snapshot of the condition/concentration of the drug at time of death.
The usual practice is to screen blood, urine and vitreous fluid concentrations along with selected tissue samples. There is a ratio and one corroborates the other. The preferred sample site for blood is the femoral vein.
If his private doctor had a laboratory blood analysis those results would be far more accurate than the PM toxicology report. If you are unable to obtain that then it is possible to research the specific drug in relation to PMR.
Please don't place reliance on the PM toxicology report without additional information.