It doesn't seem to clearly say totem-pole, open-collector, open-drain, etc. I wanted to place a pull-up at the output to guarantee a default state, but I feel like this is a bad decision.
It's push-pull output (as would be expected, unless otherwise stated). You can see how push-pull it is from the datasheet:
At 4.5V supply it can sink or source up to 32mA and (Table 7.5) the maximum/minimum voltages under those conditions will be 0.55V/3.8V. So, it's a little better at sinking current than at sourcing it (<550mV drop sinking 32mA and <700mV drop sourcing 32mA).
Adding a resistor will do nothing under normal operating conditions (chip is powered) but waste power when the output is low.
On the datasheet, under "Recommended Operating Conditions", it lists "High Level Output Current" for various conditions. When its output is high, an open collector/drain part effectivly is disconnected from its output pin, so has no high level output current. So this part must have a "totempole" output circuit.
Under "Application Information", the datasheet shows the part driving an LED connected to ground - this won't work with an open collector part.