The point is it wasn't up to turkey to decide by way of force...Turkey was a guarantor...And this why we had guarantors...in case shit hit the fan as it did...
Personally, turkey made a blunder...It would have been a different story had turkey stood by her signature...wouldn't you agree?
Post coup and invasion, a lot of personal and official rewriting of history happened.
You can not rerun history, but what would have happened if the coup had succeeded. A lot more GCs were at least passively in favour of it than it is now popular to admit to. With strong Greek support, it could well have succeeded. It didn't collapse until 3 days after the invasion, when Greek support turned out to be a hollow shell - but few would have thought that at the time.
Legally, Turkey had every right, by treaty, to intervene (and probably had the right since 1963) Morally, If the coup had succeeded, the life of TCs on Cyprus would have been a very unhappy one. Perhaps more importantly for Turkey, it would have been ringed by potentially hostile countries. And finally, the Turkish government stood a real chance of being toppled, either by the military in the short term, or at the ballot box in slightly longer term. The Turkish government really had very little option but to intervene, especially after Greece had been intervening for so long.
If their was an error, it was either by the British rescuing Makarios (I have never understood why) or by Makarios tearing up what little prospect there was of a GC-TC agreement to a BBF (or whatever would have finally been agreed) on his return to Cyprus. There is more than enough blame to go around all the leaders at this time, so don't think that I am putting it 100% on Makarios, but he was the principle block immediately post-74, and from there on positions became more solid.