Although I agree the authors could have done homology modelling, in this case AlphaFold is already doing that. It knows all the related sequences (through the sequence database similarity graph that it embeds) and has a very sophisticated modelling system. In my guess (I'd have to check with my old friends to be sure) it does as well as if not better in producing atomic accuracy for structural predictions for homology modellers better than a typical modeller could produce.

This paper is mainly a flag planted so they can claim they landed on mars first and fastest.