Au contraire! Getting an explicit CEQA exemption is a great thing if all you are doing is stringing wire (or, I presume, doing something else that supports zero emission operation, such as battery train support or on-line hydrogen fueling support). And really, the exemption just builds on the basic one that applies to whatever you do to a railroad within existing right of way and makes it clear that just adding wires (for instance) does not by itself constitute a project requiring extensive studies under CEQA.

Wouldn't have helped Caltrain a lot, though, and probably won't help other Really Big Jobs (such as some wish-fulfillment project to electrify Metrolink). Those projects have components that are outside of the original right of way, such as electrical substations and "landside" station improvements and maintenance facilities. That off-r/w work has to deal with the normal process, which could include exemptions of one kind or another (there's a long list in the CEQA Guidelines) but more likely (as a total project) would need a mitigated neg dec or EIR.

It's a good start, though, and if the railroad already has a bunch of surplus property in the right places you could drive a fairly substantial project through the exemption. Just be prepared to defend it against the NIMBYs who want to claim that unusual circumstances override the exemption (that can happen with any categorical exemption from CEQA, though with statutory exemptions like this one it's more difficult).