Literally one of the most proven truths in medical science is that LDL levels has an almost directly relationship with CVD risk over the long term. Someone with low cholesterol can of course still have CVD, but their odds are much better than someone with high cholesterol. And of course the damage from cholesterol is additive, so the earlier you control LDL, the more of a benefit.
>A new national study has shown that nearly 75 percent of patients hospitalized for a heart attack had cholesterol levels that would indicate they were not at high risk for a cardiovascular event, based on current national cholesterol guidelines.
The damage from high cholesterol happens over decades. Yet the people who actually have heart attacks are often older.
So yes, if gramps spent his life with high cholesterol but now he barely eats and is sedentary, he might have low cholesterol now but that says literally nothing to what you're claiming it does.