With the software they use, they can do it much quicker. However, even assuming they can't, they have ways to obtain your private keys and other information once you use the relevant password to open the .rar file. It is not safe. A hardware wallet such as Trezor is more secure.
Yes, the article debunked that too. Winrar actually somehow made each cracking effort wayyyy much slower than the software permits.
If only I can find that article again...
Edit:
And yes, that's why it is recommended to generate many addresses with equally distributes BTC in each, so that each of them is used only once for an unavoidable transfer.