Well let's not focus on your text but on the actual question here about $\ce{N(OH)3}$.
I can only give you some ideas here but not a definite answer.
Whenever we have tests for our first semester students there are some who forgot what a nitrate was, or nitric acid. But as we ask for a nitrate as trivial name an ortho-nitrate is an accepted answer as well. And many people will just try to balance things with $\ce{X(OH)_n}$ until it fits. It's not wrong in a test but we have to think about these compounds.
Let's take silicates. There are ortho-silicates, so salts that derive from the ortho-silicic acid $\ce{H4SiO4}$ or $\ce{Si(OH)4}$. If you try to make this acid however it will start to polymerize while water is being produced. The reason for this is that you have a positively charged $\ce{H^+}$ that can be deprotonated easily close to an $\ce{Si^4+}$ center in your $\ce{Si-OH}$-bond. Hence two of these centers will react to something like $\ce{Si-O-Si + H2O}$ until something like a meta-silicic acid forms.
Now going back to our nitric acid first with $\ce{N^{+5}}$. We know the acid is called $\ce{HNO3}$. If we add a water to this we will get the ortho-nitric acid $\ce{NO(OH)3}$ or $\ce{H3NO4}$. Much as with the ortho-silicates we can find examples like the compound $\ce{Na3NO4}$ which could formally be the salt of the ortho-nitric acid.
Now if we want the same for nitrous acid $\ce{HNO2}$, well let's add water $\ce{H3NO3}$ or $\ce{N(OH)3}$. Does it exist? Well there is a salt $\ce{Na3NO3}$. The problem is, this is no ortho-nitrite but an oxide-nitrite $\ce{Na3[NO2]O}$.
I can't tell you however why there hasn't been an ortho-nitrite formed, yet. These ortho-acids are just not very stable.