Unless this GP also has a PhD in microbiology or epidemiology I wouldn’t class him as an expert in infectious disease.
Tbh, even a basic grasp of statistics would be a help.
But the real problem, OP, is that his argument is full of straw men. It's easy to argue that the death rate from Covid was never 36%, or even 14%, but not really relevant since no one ever argued that it was. Even at the beginning, when infection was endemic to communities it had infiltrated without anyone knowing, and hospitals and ICUs were overwhelmed, and no one knew how best to treat it, the death rate was considered to be about 2%, which is considerably higher than seasonal flu, say, and combined with its infectiousness had the potential to lead to a lot of deaths (far more than we actually had).
Now that we have a community testing system in place, albeit not exactly a 'world beating' one, and an idea of how best to treat severe cases, and a vaccine is probably in the pipeline, the risk of dying from Covid is probably lower. However, what we know now that we didn't know originally, is that dying from it is not the only bad outcome. There's more and more evidence that many more people than actually die suffer, and will continue to suffer, with chronic illness, disease complications and long-term health vulnerabilities. This will probably end up being the bigger cost of Covid, perhaps for a very long time indeed.
So, in summary, YABU. Lockdown saved thousands of lives. If it had happened sooner and been more strict, it would have saved even more and probably been less damaging to the economy and the educational picture. Unless we want a tsunami of medical issues within the population for decades to come, we should still be very careful of Covid until an effective vaccine is available. And, in my view, we should also take a cold hard look at the way human society's habits are causing zoonotic virus outbreaks.
If you really think your doctor-sceptic chum's views are 'gaining momentum' then you're listening to the wrong people.