Whether tofu is a possible choice depends on where you live.
There are many places where tofu is more expensive than meat, e.g. in Europe, so in such places tofu is not a rational choice.
Even where it is available at a decent price, tofu contains much less proteins than dry legumes or meat, so a proportionally larger quantity of it has to be eaten.
Its only advantage is that it provides little energy, but it is more difficult to combine it with cereals to provide all the needed proteins, because both have a low protein content, so the sum per day of e.g. wheat bread + tofu might need to be more than 1 kilogram.
Achieving an adequate intake with bread + tofu + dry legumes is somewhat easier, because the dry legumes have a higher protein content, but one still has to eat much more tofu than the meat that would have been needed in the same combination.
I think you're overestimating the amount of protein that's required to be healthy, it's around 0.8g/Kg body weight^. So for a 75Kg person that's only 60g, 240 Calories.
