Have not used this product but agree that the potential for problems exist. This is not the only such product on the market.
Is there a way to protect against it? Yes (with a caveat). All the built in security in the world that an operating system provides doesn't do you any good if a potential miscreant has physical access to your computer(s)/server(s).
The actual security steps to be taken will vary depending on where the computer is, what its primary usage is, and who its primary users are.
The first key to these types of products is that you MUST have physical access to the computer(s) the product will be used on.
The second key is the scope of the changes that can be made. On a workstation, the only password that canbe changed is the local computer administrator account. While this will allow the miscreant to gain access to that computer, it doesn't enable access to the network or other computers. Obviously if this is done on a domain controller, you have a whole different set of issues. That's why your servers should always be behind locked doors.
To protect individual workstations, you can insitute the use of BIOS passwords. The correct password must be entered before the boot-process begins.
So in summary: Be taking advantage of all availale physical security measures, yoiu greatly reduce the potatnetial impact of the use of these types of products.