Still, tou are saying you need them to follow you off the edge to get a stock off /advantage, just because they will likely follow you off (which you claim is your experience) doesn't mean Samus has the advantage in the match-up, rather it means the Falco is unknowledgable about the current situation and the rather large advantage Samus has in it.
For stage fighting you said you have strategies that you can use against Falco, but you also said that as soon as you see a laser you run back off the edge, that is you being well-informed on the advantage and doing what you can to even it out. Personally I don't spam lasers for their damage but rather I use them to approach or make my opponent approach or sometimes frustrate, lasers aren't for damage, they are for throwing the foe into an unfamiliar setting and taking advantage of that to get in real hits.
By saying you would run off the edge when you see lasers (because you know you just lost the advantage) and that the Falco would follow you off because he doesn't understand the disadvantage is measuring people of different abilities against each other, which is not how match-ups are determined, you have to take people of the same skill level and knowledge and see how the characters fare then.
Samus has advantage off-stage, but not to a sufficient amount where she is going to gimp Falco every time he is trying to recover.
Falco has advantage on stage, Samus is a pretty slow character whose height also adds to her difficulty with lasers, to add on to this, samus's projectile game against Falco is largely shut down due to the reflector (sure she can still throw some stuff in here and there but she won't be spamming it all day like it is safe to do against some characters)
The match will eventually be forced onto the stage if neither character wants to go to the other's area of comfort, even if the only reason is that Brawl in general is played on the stage, that is sufficient enough to make the ledge sitting seem like stalling and the waiting falco on the stage to be just waiting for the stalling to end.
Therefore the advantage goes to Falco
I don't know how the hell you manage to get people to follow you off the stage, I play Samus here and there against my friends and they just kind of just sit on the stage and wait (I guess because they are aware of the danger, but still, I want some off stage gimp kills for fun)