I'm well aware of how Sakurai doesn't just look at 1v1, but the same applies, especially going off of the Screw Attack.
Again, you're decontextualising and singling out my statements.
I said that his opinion is wrong because literally everyone else disagrees with it
for factual reasons, and based on analyses performed by various people.
It's also worth nothing that literally EVERY player at the Invitational disagreed with him and had the opposite stance. While nobody played as her in the Invitational itself, all of the players got a whole day to play the game before the Invitational and could try out any character they pleased, both 1v1 and FFA...which explains why Samus isn't represented in the Invitational, nobody thought she was viable (keeping in mind the Invitational was both 1v1 and FFA...primarily FFA actually). The video below represents this.
And while it may be his "opinion", opinions can indeed be wrong or nonsensical if they don't reflect the facts on the subject matter, and therefore, they are invalid. This appears to be the case with Sakurai's statement on Samus in the E3 build. Literally nothing supports the claim and all facts indicate that the opposite is true.
I haven't seen any videos of it KO'ing from particularly early percentages in the E3 build, and it's primarily a move designed for trying to KO people already in the air anyway. On it's own, it wouldn't make Samus the best in the game, especially since it leaves you in free fall. This is a move that definitely isn't as powerful as any of Bowser's strongest moves even in the E3 build, and leaves you WAY more open due to propelling you in the air and leaving you in free fall. Even if it was stronger than it is now, Screw Attack didn't make Samus the best in the E3 build, not by a long shot.