The Dhammakaya citiya is built correctly by the standards in Buddhism in every way. It is not a deviation from the traditions and the Buddha’s standards in any way. In Buddhism, there are 4 kinds of cetiya.
First, Relic Cetiya contains the relics of the Lord Buddha, or the remains of an enlightened monk. The Dhammakaya Cetiya contains the relics of the Lord Buddha
Second, Memorial Cetiya contains the necessities of the Lord Buddha or enlightened monks such as alms bowl, robes, and other necessary belongings. However, those items are rare and difficult to acquire in the modern age. The Dhammakaya Cetiya contains the necessities of modern monks, so that a thousand year from now people would see the way of life of monks in this era.
Third, Dhamma Cetiya contains the Tripitaka, or the Buddhist Scriptures. The Dhammakaya Cetiya contains the Tripitaka in several different languages, including CD-ROMs of the teachings in Buddhism today.
Fourth, Votive Cetiya contains the statue(s) of the Lord Buddha. The Dhammakaya Cetiya is covered with 300,000 Buddha statues.
In conclusion, the Dhammakaya Cetiya may be considered as all 4 kinds, and is not considered as a non-Buddhist cetiya in any way.