The only (informed) argument I see for that position is something along the lines of "this acts as an endorsement that such data storage is fine, and will encourage people to do more of it. You can observe that this effect has already happened with a large increase in op_return activity since the pr was opened, and the creation of a new "op20" token scheme. That endorsement will flow over to schemes that use witness data, increasing their use as well. That will make it less likely that will have non-full blocks (due to more token usage of either type) and increase the data storage requirements of non-pruned nodes due to increased witness usage"

Personally, I think the immediate observable effect is due solely to the publicity the issue has generated and will disappear when attention moves elsewhere.