Baseboard: replacing a 4-wire thermostat with a 2-wire thermostat

Hello,

We have a cabin with two baseboard heaters connected to one basic 4-wire thermostat. I'd like to install a new internet-connected thermostat so we can crank up the heat a few hours before we arrive at the cabin. I found a reasonably priced digital baseboard thermostat that fits this requirement. However, it only comes in a 2-wire model.

The manufacturer advised that I should connect the two black wires to each other within the junction box and the two red wires to the new thermostat.

Does that sound right? I just want to ensure the manufacturer is not risking my safety in order to sell me a new thermostat.

Thanks,
Matt