Yes, you are correct in your surmise about the meaning of the quote! It is saying that doubt paralyzes us. If we are constantly plagued with doubt, we will never make a mistake, but we will never make a decision either. Another famous writer, William Shakespeare, also made a similar comment about doubt in his play Measure for Measure, noting:

Our doubts are traitors, and make us lose the good we oft might win, by fearing to attempt.

Doubt is a cop-out, and Pi, who loves belief (as in religious belief) as much as he loves science, doesn't endorse doubt.

The full context of this quote shows Pi's irritation with religious agnostics in particular. Doubt, he says, has its place, but after a certain amount of time it no longer is helpful to us. Putting the quote in context will help us see how Pi applies it to religion, though it can easily be used to describe other situations:

I'll be honest about it. It is not atheists who get stuck in my craw, but agnostics. Doubt is useful for a while. We must all pass through the garden of Gethsemane. If Christ played with doubt, so must we. If Christ spent an anguished night in prayer, if He burst out from the Cross, "My God, my God, why have you forsaken me?" then surely we are also permitted to doubt. But we must move on. To choose doubt as a philosophy of life is akin to choosing immobility as a means of transportation.

Yes, you're certainly on the right track. Choosing not to move as a method of moving will get you nowhere. It isn't a possibility because "immobility" isn't even a form of transportation. Using Pi's comparison, doubt would not even be a choice as a philosophy of life. Doubt would indicate an uncertainty of belief or an inclination not to believe, and we know this is not true in Pi's case. His life is defined by his interest in and dedication to religion and his experiences on the lifeboat.

All through the book, Pi seeks to find the meaning of life. He had to make some difficult choices while on the ocean that went against his earlier beliefs, such as eating meat and human flesh.  The meaning of his whole life is determined by the story of what happened after the boat sank. He tells two different stories to the men that represent the choice between believing in God or not believing. The men choose the story with animals as "the better story", and Pi adds, "And so it goes with God". This is why doubt can't be a choice as a philosophy of life.