I don't think the list is for safety reasons. That would imply that anything not on the list is unsafe - if that was the case they shouldn't be on sale at all.
The list is for the fairness of competition, rightly or wrongly. My interpretation is that if a battery is on the list, it is commercially available in the UK and as such any competitor has an equal chance of using it, and winning races. It rules out military spec batteries with higher energy densities that are not available to the general public, for example.
The question that I think needs to be answered is, must the importer be the person to submit a battery for homologation? As a private individual why can't anyone buy some batteries from a UK importer and ship them to the BRCA for homologation? They simply absorb the homologation cost from the importer, who may be completely disinterested in bothing with BRCA homologation.
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