One difference between the threat model of the original query and your response is that if someone hacks into BigCo and accesses the digital records between you

One difference between the threat model of the original query and your response is that if someone hacks into BigCo and accesses the digital records between you an BigCo then they know about all of your transactions with BigCo. If they hack your home document system then they know about your transactions with BigCo and with every other company you have ever done business with. The level of paranoid protection being suggested is probably not warranted, but unless you can think of a good reason why you would need to access these docs remotely it is probably a good idea to keep the drive with this data separated by an air gap from your systems when it is not in use...