My sense is that we have Sinclair narrating from some point in the future. The transition of grammar takes place as we push into the station. from the outside in. This was the last of the Babylon stations, and this particular segment of it is set in 2258. (Season two would say, "The year is 2259." And so on.)
Many here will remember a show called "You Are There." The usual narrator would say, paraphrasing here but keeping the grammar, "The year 1776 was crucial to our nation's history. The founding fathers were on the brink of declaring independence. It's a moment of great importance. The year is 1776...and You Are There." It's along those lines. The purpose of the narrative changes to transition us into the story.
The tense shifts are intentional, and go with the scenes we're seeing. They're *supposed* to shift, with the visuals, in order to bring us into the present from the future, at which point this story is being introduced.