What is the unique clustered index on that table? If the table is never written to - how did the data get in the table in the first place? A table with no data won't have any fragmentation.
If you are assuming that an identity column set as the clustered index somehow prevents a table from experiencing fragmentation - that is not correct. If you are assuming an identity column prevents fragmentation when the data is loaded, that too is incorrect.
A good example is a load process that goes parallel - that parallel process can and will load data out of order. The only way to ensure that a clustered identity index does not fragment when the table is loaded is to load the table one row at a time.
If the clustered unique index is not an identity column - the only way to ensure no fragmentation when loading data is to again, insert a single row at a time in the clustered index order.
Once loaded, an offline rebuild of the table should remove all fragmentation - unless mixed extents are used for that index.