No, it isn't. An open WiFi will most likely not be used by someone trying to do something that might be either illegal or piss off some powerful entity whereas a Tor node will be just that.

So you need to weigh whether or not you want to do this a bit more carefully than you would if you left your WiFi open. On top of that an open WiFi will likely not get you blocked by default from a ton of other online services but running a Tor node will get you blocked from plenty of services in a hurry.

This because Tor for most regular website equates to 'people that we have already gotten rid of using other means' or 'people that are up to no good'.