I think the Author is somehow misleading, if I want to re-use a wallet address multiple times for transactions, it doesn't give me any security harm to my private keys, also we have not seen any computers who have done that currently except for Quantum computers that have been making news but it is still hypothetical, nothing has been done so far. However, address reuse is a big concern when it comes to privacy, you cannot preserve privacy by using a single address for incoming and outgoing transactions every time, the chain surveillance are watching the network, and the moment you do that, you can easily be detected as the owner of the address and the big problem is that you wouldn't be able to combine it with other UTXOs as soon as that address becomes expose to chain analysts.
So, technically, don't use an address more than once.


A node can carry out a transaction Malleabity by changing your transaction ID on the network but they don't have the strength to extract the signature from a transaction, this point is kind of too off.