[rx_tx]

What do you do with the added deltaV from the venting? (not sure if significant) It could send the already-out of control rocket stage/object to a weirder or worse orbit, increasing the changes of collision.

[mandevil]

Ideally you have several vents perpendicular to the orbital path and open them at the same time, so the vectors cancel out. That's the happy case. If, because we are in the sad case, we can't get that, it's still better to have one piece of debris versus thousands.

[gpm]

Shouldn't the happy case be "we know the orientation of the stage so we can vent in the direction we are travelling to accelerate deorbiting"?

[Filligree]

The deltaV will out, one way or the other. Venting is better than having it completely uncontrolled.

[Evidlo]

Vent for a while, then use the reaction wheels to flip and vent in the opposite direction.