As always, history's interpretations vary from historian to historian, this is mine. Take it with 2 grains of salt.

Great question! It is true that Nicholas II is never shown in a positive light, my own personal conjecture is that Nicholas II is like Louis XVI, that in different times they would have been unremarkable, passable figures in history who were merely a name in a book. Unfortunately, that is not how history placed him.

Nicholas II reign followed his father's, Alexander III, who could be described to rule Russia with both of his fists and never letting go for a second. He was hard and was feared. He was the one who centralized the government, weakening peasant and noble influence.

Thus was Nicholas II reign for a period after his fathers death. The sheer momentum of his fathers legacy shielded him and his new family for a bit. Russia was delighted for a new Tsar, and ignoring whatever superstitions they held, they believed in him.

Of course, it all went downhill with Bloody Sunday and the Revolution. The population had grown aware, in more ways than one. "...six out of every ten laborers in Moscow were literate..." (Fleming, The Family Romanov, 59).^^1 They still believed in the Tsar, simply all they had to do was march to the Tsar and petition him. Of course, the Tsar was not in St. Petersburg at the time, but it did not matter for the soldiers who fired into the crowd. This was the beginning of the people's distrust for Nicholas II.

As you can see, it's not that Nicholas II managed to create some sort of elaborate ruse or strategy to "survive", he did nothing.^^2

He was lucky.

No doubt that Nicholas II was always teetering on the edge between Revolution and Peace, whenever it seemed that a strong wind would blow him over, he somehow held up. Through several bouts of wind he stood, however I think that you surmise correctly when you say that a vacuum at the top feared all. Thus, no one was ever brave enough to push when the wind came.

When the Duma came, the people were satisfied for a while. The third Duma was the one that stuck around for five years from November 1907. This Duma was filled with "feudal-minded landowners" (Lenin, Vperyod, No. 18 1907), thus the aristocracy and bourgeoisie never had a reason to oust the Tsar.

There were no doubt people who wished to oust the Tsar, but I think that, like in other periods, the attempts were feeble and could not even bring themselves to be written into history. When Nicholas end came, it came swiftly.^^3

In the end, it's most likely luck that gave him life. People speak of him negatively, but he was not a bad Tsar, he was just the wrong man in history. For that, he did not survive.

^(1. This is taken in context, though not quoted directly from W. Bruce Lincoln's In War's Dark Shadow: The Russians before the Great War. )

^(2. Actually, though he might not have done it on purpose. Nicholas II persecuted the Jews, and like Hitler, may have blamed them for the wrongs in Russia, which could have helped bring the Russian people to his side, though I am unsure of this.)

^(3. Nicholas II did not die immediately, though you probably know this. However, Nicholas did try to hold the throne himself. He was not given the option. His troops did force him to abdicate in the end, after the catastrophic failure of The Great War.)

Edit : If I have "err'd" please help me correct my mistakes