What's the deal with sabbath oven mode?

Not really. The issue is that it is forbidden to 'create a spark' on the Shabbat, but if something is already running/lit/on, then you are not creating, just using.

My cousin is an Orthodox Rabbi and he used to unscrew the bulb in the fridge, since it would light when he opened the fridge door. The fridge, on the other hand, was already running when Shabbat occurred, so he wasn't creating that spark. In addition, in order to have hot / warm tea through Shabbat, he would keep a foil pan on the electric burners, put the burners on low before Shabbat, and then he would keep his water heated.

Keep the Sabbath holy.

Exodus 20:8-11

SDA

Legalism. It actually wasn't acceptable before Christ, and it isn't acceptable after Christ.

The laws of God are to be written on our hands, our hearts, and our minds. Looking for technicalities to make the Sabbath less "inconvenient" is legalism for sure and straying away from the "I want to" aspect God intended and going into "I have to" and trying to find ways to get out of doing it.

Unacceptable.

Yeah, my new fridge has "Jew Mode" also. Rather annoying.