They raise a number of concerns. In particular, that whilst steps to block companies from the supply chain if they do not have identifiable beneficial ownership are welcome, they then note that:
the clauses on toughening up the exclusion of businesses displaying poor tax conduct are weak in the extreme. Nothing at all on tax avoiders.
Tax avoidance is, by definition, legal. Why should someone be barred from supplying government if they are, by definition, obeying the law?