A point. Even though yes, LN and BAF have 90% on each-others cells, there is an agreement that we do not let each-other use the tech cells without being official faction or making a serious request. This tech cell case is also during the Gallia war, so the time leap back to 810 is a bit off.
A pointer. The ship is being said to be 810, and is a "Dunkirk", now Dunkirk is actually the most advanced ship in Sirius due to it being a recent design of warship, next to I believe the Overlord. There is however precursor models for all Battleships of house navies, indicating there are ships that share the basic design, but are less advanced. This is common in military production.
I can't seem to find all the relevant information for this, but one thing is certain, the model prior to Dunkirk was "Victoria", this is the model used by the Battleship Hood and also the Battleship York. It is hard to be an exact date on the Victoria class of Battleship, but it is safe to say there are no more being produced and it has been phased out in favor of the Dunkirk. The Hood was damaged some time after 752, so the design is 70+ years old.
So I would say you could potentially justify acquiring a to-be scrapped Victoria, which is out of date as a design and not a risk in terms of military technology being stolen due to its obsolete systems which the new owner would likely replace with Liberty based systems.