Confused about What Lavelle Mentioned in class

[Hannah Guo 3D]

Can anyone explain the following statement? It's in Lavelle's class notes.

If [H3O+]< 10^-7 then solution is considered neutral because we know autoprotolysis generates 10^ -7 mol/L H3O+.

I understand how we get 10^ -7 mol/L H3O+ in neutral solutions, but I don't understand the first part of this statement.

Please explain. Thank you!

[Curtis Wong 2D]

Since the concentration of hydronium atoms will be so small, that they will not make that huge of an impact on the pH level of the solution. This only works if the concentration is way smaller than 10^-7, ie like 10^-10, in which subtracting that from 10^-7, will not impact that severely leading to a pH of still 7 and still neutral.

It might be slightly acidic but again the impact is minimal.