You also have to be sure the machine you're hosting this on won't be taken down if you really die and aren't around to manage/pay for it anymore. Server in your closet? The plug will be pulled long before 6 months pass after you're gone. Server in a data center? You can't be paying for that monthly, as chances are your credit card will be cancelled and your machine will be shut down for non-payment before your 6 month deadline. Also, hardware failure makes it a possibility that your server will not survive 6 months uptime anyway.

Basically, dead man's switch is not even remotely guaranteed to work.