Ah, OK. Hadn't noticed that little g at the end of electrumg. Didn't know they had a BTG tool.
If by "they" you mean the "Electrum" devs... then NO, "they" don't have a BTG tool...NONE of these Electrum "forks" are the work of, nor are they supported by, the Electrum Dev(s). They're mostly released by the devs (or supporters) of the fork coins. Also, they're prime targets for fake/scam clone wallets designed to steal seeds/keys/coins... Electron Cash had a lot of issues with scam clones to start. Be careful and make sure you're downloading "official" versions of wallets.
And it looks like I could have saved a lot of time if I would have used the Electron Cash wallet to extract the BCH. :PWith this wallet you wouldn't have to download the blockchain. Once you have the Armory private keys exported and arranged in a note pad file, you would have the coins in minutes. If the wallet hasn't been tampered with. https://electroncash.org/#download
Fairly sure that is what I recommended here: https://bitcointalk.org/index.php?topic=2070058.msg35363497#msg35363497 
In general, if you have NO interest in continuing to use any given Fork... using a light weight client (ie. some Electrum derivative, or Coinomi etc) is a much easier solution than attempting to get Armory to interface with the forked blockchain.
Granted, you need to make sure that your BTC has been moved first, but that's a relatively straightforward task (create, sign, broadcast transaction)... and generally much easier than attempting to sync a whole new blockchain.