> if would have been a glitch that would cause the program to halt unexpectadly, the engines would have remained running

I don't know about that. I've worked on systems where there is some hardware with thruster duration that software is writing. So if software crashes, the thrusters stop. (But I have never worked on a lander). If software is running the control loop, things would get very bad if the engines kept running at their previous output levels for 27 seconds. Thrusters are never aligned perfectly, who knows what kind of rate the lander had, there may be wind pushing it, etc. If a thruster blindly kept running, the lander may have spun up, flipped over, etc.