If it was purely poetic language, why the Roman objection to Atilla being compared to a God? Feel like there has to be more to it than that.
The "dispute" was about status, not a simple ontological fact. The Roman did not grant Attila the same rank as Theodosius. Calling him "God" means that Theodosius has the highest rank possible, but Attila not.
Note also that Roman emperors could be given the epithet "Divus" ("the divine") after their death well into the Christian era. The German Wikipedia has a list: https://de.wikipedia.org/wiki/Divus Although Theodisus II is not included, there appear two East-Roman emperors after him: Leo (†474) and Anastasius (†518).