so now I'll commit heresy in the eyes of some....
Malt whisky is a drink not a religion. Drink it however you want. Straight up, on the rocks, with water, with coke, with ginger ale, with whatever the hell you like, make Manhattans with it, or whatever cocktails take your fancy, and shock! horror! serve them on the rocks.... I do. I might blanch at the idea of mixing a 25 year old single malt, but I might not, it depends on my mood and what the final drink is.
There are no rules. Drink scotch how YOU like it; and ignore the nobbers and the whisky snobs who tell you otherwise.