I doubt this purchase made any impact on BTC value.
Roughly $110,000 at today's value. I hope that was a tasty pizza.
That is like saying "Grandpa your an idiot for spending a dollar cause now that could be worth $500 (I am making up numbers for the example)" You have to think, that a year in time, is a long time in the bitcoin economy. Just like 70 years is a long time to hold on to money now.
How could one dollar be worth 500 dollars, it will always remain one dollar, unless the value of USD drops to 0 and we're all using bitcoins in the future, in which case your grandpa sounds like a pretty smart fellow to offload it while it still had value.
I think you need to call him and apologise young man.