From day one PLoS ONE can allow as many SI files as anyone could want just so long as no individual file is larger than 10MB--that is no more than we have available on all PLoS journals

The relevant policy section actually says "All supporting material...should be smaller than 10 MB in size because of the difficulties that some users will experience in loading or downloading files of a greater size." This implied to me that the TOTAL should be less than 10Mb, not that each individual file should be less than 10Mb. For the sake of clarity you might want to change it to something like "All supporting material... should be composed of individual files no larger than 10Mb...".