Simply a matter of them not pressing a iron gear at the end of the solid roller cams like they do for other fitments. Evidently, they do that for the FE hydraulic rollers but not for the solid rollers (must be a low volume thing comparatively speaking). So the bronze gear is used and becomes the sacrificial lamb instead of the expensive cam (has nothing to do with
oil pump other than the fact that the bronze gear can't hold up to that extra strain). In racing, no big deal...they can swap the gears out every time they tear down the motor (often).
Today...there may be polymer gears for FE solid roller applications. Not sure they've been run enough to prove long term durability just yet. People keep posting how they have no problems using steel or iron gears in their FEs with roller cams, and then we discover they are running hydraulic roller cams rather than a solid roller.
If it was me, and I wanted to run a solid roller in an FE for the street and had to run a bronze gear...I'd go with a dry sump.