More likely coincidence than not.
"Titan" is a word that is generally used to indicate a deific sort of stature. In the case of ships, it would be a pretty evident and cool way of saying that something was "really big". Thus, if you have a really big ship, there's only so many things you could call it, and "Titan" is one of them. And for marketing purposes, "Titan" is a pretty good thing to name a ship. As for declaring the ship unsinkable, that's generally a well founded assumption with things that size, though it turns out to not hold as true for large ships as it does for cities or other great constructions.
Being over 800 feet long, having 3000 passengers, and not having enough lifeboats while considered unsinkable are all very related quantities. Assuming the book was holding a pretense of being reasonable, it turns out the first two values are pretty good estimates of what you could actually make in that time period, as evidenced by the Titanic itself. As for not having enough lifeboats, that can be reasonably justified by whatever reasons the actual Titanic did not have enough lifeboats.
I'd blame it mostly on the Law of Large Numbers: which correlates to that if something is possible, it'll inevitably happen eventually. The only oddity is how quickly the description of the possibility became actuality, but seeing as it was a more or less singular event it falls under the Law of Large Numbers as well: freak accidents are possible, and will happen eventually.