If you look at a diagram of CYYZ, you will see that the extended centreline of 24L does not intersect the 401 freeway for over 1km from the end of the runway/ravine. To 'go on to' the 401 would have required a 90-degree slew. IOW, media hype.
Hold on... The photo on page A11 of to-day's Globe & Mail shows the AC DC-9 that went off what was then 23L on June 28, 1978 (the runway has been presumably re-aligned since then). If you look at the picture you can see the skid marks of the aircraft at about a 40 degree angle to the centreline of the runway.
Now take a look at the scale diagram on page A8. If the 340 had gone off the runway at 40 degrees it would have gone into the middle of 401 in rush hour.