This doesn’t make any sense: it’s not prone to start losing it at 70, because the spoiler deploys.
I suppose that might make you leery of driving the car at its top speed with the spoiler broken, but if the spoiler’s functioning, what’s your worry?
And which version of the CRX came with a spoiler? 
And the Porsche 911 did not become the Boxster.
Well, it did, sort of, in that the front end styling was similar on both, such that you can’t really tell the difference without reading the badge. Previous Porsche models (944, 928) were always quite distinct in styling from the range topping 911, which maintained some air of exclusivity for 911 owners. That was lost when the front end styling was homogenized, and the Boxster, Cayman, and 911 now all look essentially the same. I take it that’s what he meant.
…but I still don’t understand the CRX-spoiler thing though.
The Porsche 911-type car is (from 1998 onward) a 3.4-3.6L (depending on configuration) rear-engine 2+2 car. The Boxster is a 2.5-3.2L, mid-engine 2 seater. They share very few parts–even cosmetics–in common, nor was the Boxster evolved from the previous versions of the 911. It is a wholy unique chassis and powertrain.
Stranger
True, however, the original Boxster did use the exact same headlights as the 911. Porsche was struggling financially back then (there was talk of them being bought out, I believe), and couldn’t afford the costs associated with designing a new set.
Of course, now that Porsche is flush with cash, that’s no longer the case - the new Boxster has noticably different headlights than the new 911.
I put a spoiler on my Ford Contour, but just because the back looked so plain without one. Now I get all the babes! (Not really, that’s my Mustang’s job. Sorta.)
Obviously a Porsche 911 isn’t going to lose it at 70mph.
The real reason the spoiler comes out at 70 is that 911 is an insanely fast car and the spoiler needs 3 or 4 seconds to fully extend. So, under full acceleration you will be doing more than 120mph by the time the spoiler is fully extended.
OK, I’m curious, so I’ll bite. What’s wrong with Corvettes with Traction Control?