Nope, Mane wasn't in a better position. Alderweireld was positioned between Mane and Salah and never committed himself. The distance between Mane and Salah was less than 5 yards, which wasn't big enough to totally take Alderweireld out the game with 1 pass.
Right.
This is the start of the movement:
Ball has been played into Salah, he and Mane are 2v1 on Alderweireld. A ball in behind Alderweireld at this point would have set Mane away and would have worked out better for Salah at the end of it. Instead...
This is two touches later:
A pass across Alderweireld makes it a footrace that Mane might win, but also brings Lloris into play. The ball behind Alderweireld puts him on the turn and gets Salah on his blindside and running at goal.
But instead:
Salah continues to carry the ball, even though the ball to the back of Alderweireld puts Mane 1v1 with Lloris.
As the move progresses, Salah begins his turn to get the ball on his left, predictably. All defenders want play to be predictable, and this plays right into Alderweireld's hands. Crucially, at this point, the slip ball into Mane puts him 1v1 with Lloris, in the box:
Even then, the situation is not irretrievable - although Mane's marker is catching up as the momentum of the move slows down:
There's still time to play Mane in for a one-touch shot. But Salah elects to shoot himself, in an unfavourable position, fully blocked by Alderweireld, with a recovering defender now ready to double-mark and also cut out the Mane option. The result - a blocked shot and an eventual loss of possession, with Spurs regaining defensive shape around their goal:
At every point in that breakaway, Mane was the better option to unbalance the Spurs defender. As it is, Salah helped to make play predictable, wasted a 2v1 situation, and Spurs ended up with the ball. It wasn't a good decision by him at all, mate. That would be a massive coaching point for a teenage player, let alone a top class professional. Now, we has entitled to take the shot, given that he did all the hard yards, don't get me wrong. But the shot wasn't the best option when he had a 2v1 situation that could have entirely eliminated Alderweireld as a factor, if he'd made a better decision.