They are whispering in my ear that this bill is the first time that it applies to Parliament. That is why it's important to keep a firewall.
The problem is that the firewall is there only for harassment, not other issues. That may seem like a detail, but it would allow an ill-intentioned minister to meddle in a political office, regardless of their party. If the suggested amendment were passed, the minister would not be able to access it when it is related to politics.