i don't believe the faster oxidation is the "primary" cause of the base side ridge marks. This has been observed with non-staining developers, D76 for example, and apparently is caused by the developer speeding up as it crosses over the ridge. This gives more energy.
Originally Posted by nick mulder
However, pyro staining developers may accentuate the problem with some films that have a heavy gelatin coating on the base. If that is the case the ridge that results from agitation will be more pronounced from staining.