If you understand the argument, you can't characterize it as weak. This leads me to think you aren't correctly grasping the argument.
If it is impossible to make a typewriter type outside the spaces required of it's gear track, then characters typed in positions which are not allowed by the typewriter can only be explained by being forged with modern computer tools, or by removing the document from the manual typewriter, and then putting it back in a misaligned manner.
You seem to think that the carriage can be released, and that characters can be typed anywhere on the page, but I believe this behavior is completely inconsistent with my experience using a manual typewriter, and inconsistent with my pretty extensive knowledge regarding how mechanical devices operate.
The typewriter carriage is constrained by teeth in a rack. That is how it advances a specific amount every time a letter is typed. This is how they make the character spacing consistent.
When you release the carriage, all you do is allow the gears to move freely. When you let go of the carriage release, the gears then go back to meshing, thereby forcing the carriage to be positioned in a space allocated for a letter, and positions in between letters are not possible.
Here's a link to typewriter maintenance and repair. Read page seventy (70) and it will tell you the same thing i'm telling you. You can't make a typewriter type in the wrong place on the page, even by using the carriage release, because once the carriage is reseated, the gears mesh back where they are supposed to be, not in between where they are supposed to be.
Again, note the carriage rack.
