In a different legal environment this would be a good approach, but currently I don’t think the courts would accept this argument, as they are trying to push Congress to legislate rules on things like this (which Congress steadfastly refuses to do). Prior courts were more willing to “legislate from the bench” but current justices have expressed concern that Congress is abdicating its rulemaking responsibility.

i am not a lawyer, but to the best of my knowledge there are specific criteria for "stalking", one of which being that the stalking causes fear or distress.

the average person (i.e. a "reasonable person" by legal definition, even if us tech folk don't consider it reasonable) is not particularly scared or distressed by targeted ads. some people even like them.

a good lawyer might be able to make something out of it, but i'm not convinced that stalking laws are the right avenue.