OP here. After discussing this with a few people I updated the post to lay out some other possibilities. It is true that Electrum verifies locally, and in this

OP here. After discussing this with a few people I updated the post to lay out some other possibilities. It is true that Electrum verifies locally, and in this case it was simply used as a replacement for running openssl or an alternative. You still need to verify the address and key, tho - and it isn't stated what the process was in this case.