Things that I'd worry about are related to reliability, safety, preservation of your investment.
1. What happens of the device is triggered on too soon?
2. What if the TPS or signal fluctuates ever so slightly so that the device toggles on/off quickly.
3. How temperature and other varying conditions affect things. Have you addressed electrical noise or transients, mechanical vibration, etc.
4. Are there conditions when the TPS could look like or actually be wide open but you would not want to turn the device on?
5. If the TPS or a wire related to it fails, will it turn on, if so, is that bad?
If none of this is a problem then a simple circuit may be appropriate. If there are other worries such as I've mentioned here (there certainly could be plenty more) you might employ a microcontroller or similar electronics to address the issues.