the TLDR: NASA spending not contrtolled on cost-plus contracts given to Rocketdyne for refurb of SSME and to Grunman for the SRB modifications.
They note that cost-plus usually given for risky projects but these two
were just upgrades of tested engines.
Not mentioned; the whole project is meant as ensuring steady funding to Rocketdyne and Grunman without need for deliverables.