So, I'm not certain what the balance intentions were on the nomad Siris Cruiser, but it has 950 cargo, which means it has to use the Battleship cloak while a similar heavy cruiser like the Rheinland cruiser has 900 meaning it can use the Cruiser cloak.
Now for the weight the Siris has in its armor, I can understand maybe forcing it to use the Battleship cloak was a design choice, but with its cargo limited to 950 you have room for the cloak and a cap 5 armor, nothing larger.