Absolutely not. It's nobody else's decision or discussion (unless the parents actually want their own parents opinions). According to you may e they should also bring 1 person from each neighbor so that they too can't come back with any complaints. As well as each sibling, people from shul, etc. Heck, they should bring me and you too!
You may be correct in principle, but the fact of the matter is they will continue hearing about it for many years to come, now is the opportunity to put the discussion to bed. The last thing they need is a parent telling them you should've done different and if you would've told the Gadol ABC they would've told you to do what I said.
Someone my father knows very well lost his wife a few years ago. It reached a point that the only remaining option was an experimental treatment that had a risk of killing her sooner. They went to ask HaRav Dovid Feinstein, and he took along someone from his family and someone from her family. (Rav Dovid said not to do the treatment, at which point he broke down crying. Rav Dovid then said "the children will grow up the way she wants them")
