And for some strange reason you have linear shaped charges all over the spacecraft...
Honestly - do you think the Space shuttle is a Hindenburg?
All stuff you are claiming, can be debunked by just throwing physics and chemistry into the room. Even if you would hit both OMS engines with the same silver bullet, you would also have to damage both pressurized tanks in a module and do it in a way, that from both tanks, liquids can leave in high enough amounts and mix. just punching a hole into the tank is not enough for a explosion. If you hit the part which contains only pressurized gas behind the screen inside the tanks, you would just have helium gas venting out, the liquids would either freeze to ice (MMH) or vaporize (N2O4) with the N2O4 gas being able to react with the aluminum before being vented outside. Not a high damage as you have low flow rates.
You also need a mixing of the two liquids in a short time AND have the liquids contained inside a volume that the gases gain enough pressure before leaving the structure. OMS propellants do not detonate, it's characteristic speed is much lower than for example hydrogen+oxygen. You would just get a very violent fire in the OMS pods if this happens.
And for ripping the wings away, remember that the Shuttle survives very high loads during reentry. That is not that easy, a violent fire with the OMS fuel can NOT do that, it would be enough to damage the aft structure before being vacuum inerted automatically.