Characterizing the premises of ideological arguments as axiomatic means that

The answer is  the premises are starting points, first principles, or assumptions
an ideological argument could be considered as axiomatic if the argument itself is self-evident and had an unquestionable truth.
This means that the premises for such arguments is usually accepted by all the parties that involved in the arguments so it could be easier for them to follow along the principles and assumptions involved within the argument