IMHO you should replace the rim. I'm no metalurgist but I do know that cast materials do not take well to bending, the metal gets brittle if it is not worked at a specific temperature.
In addition, I have seen rims that were "straightened" professionally and I wasn't impressed. While they did get rid if the flat spot so there was no hop on the spin balancer, you could still see lateral run out as a wobble. These rims were from a bike that was crashed hard on a track but if they were that bad, they shouldn't have tried to fix them.
Rarely is the question stupid, but sometimes the answer is
you need to run everything you read online through your own personal BS meter to determine if it makes sense to you.