In the linked statement there are exactly two mentions of decolonisation.
Firstly on p6:
> Values of EDI [Equality, Diversity and Inclusion] should permeate the curriculum and every aspect of the learning experience to ensure the diverse nature of society in all its forms is evident. MSOR providers should reflect on their curricula and processes to ensure that no group is disadvantaged or othered; for example, decolonising the curriculum can involve explicit reflection on the history of MSOR knowledge generation, as well as reflecting on how delivery or admission practices might adversely impact on certain subgroups within the student cohort. EDI aspects of student engagement and achievement should be monitored and actions formed to ensure equity.
Then on p. 7:
> the curriculum should present a multicultural and decolonised view of MSOR, informed by the student voice. Where possible, it should present the work of a diverse group of MSOR practitioners. Students should be made aware of problematic issues in the development of the MSOR content they are being taught, for example some pioneers of statistics supported eugenics, or some mathematicians had connections to the slave trade, racism or Nazism. Students should be educated in general EDI matters and also those that are specifically elevant to MSOR, such as the need to consider diversity in data collection
and analysis.
I sympathise with the idea that this isn't particularly relevant to the content of mathematics. But I see nothing in the above that suggests social constructivism or challenges objective knowledge.