Fundamentally on the physics level you are right. LNG regasification is not hard tech. It doesn't require unobtanium, probably any technologically advanced country can develop the necessary know how if they need it. Heck, at small scale you just pour the LNG out in a puddle and it will turn back to gas. :)

But building any kind of infrastructure takes time. There are some factors which make it more complicated engineering wise: cryogenic fluids, handling large quantities of flamable and explosive liquids and gasses, being built on the waterfront etc etc. None of these are insurmountable mind you! They just complicate it a bit.

One way we can look at is by comparing how long such plants took to get constructed elsewhere. I looked up a few European examples. From the first announcement to the first ship docking:

  UK/South Hook ~6 years
  UK/Dragon ~4 years
  UK/Grain ~6.2 years
  Belgium/Zeebrugge ~10 years
  Netherlands/Gate ~4 years
  Poland/Świnoujście ~9 years

(I have collected my sources on a spreadsheet here: https://docs.google.com/spreadsheets/d/1md_XfmrpIYhWj72Mu3BJ... )

Probably I made some mistakes in the above, and there are some inconsistencies (do we count until the first commercial ship, or the first ship trialing the facilities?) Also I assume that all of these things can be done a bit faster in case of a dire emergency. But it seems even in that best case it might take multiple winters until a regassification plant is up and running. Which is a bit cold and scary.