You don't. The Guitar-Police will knock on your door and take you away
😉
Well, I never had good results with quantizing acoustic guitar but I don't have typical rhythm tracks, so there are no regular peaks that could be used for an automatism. Quantizing does rather work for percussive sounds with clear regular peaks and not much between them.
You may try the quantize function and make it a little loose with the advanced settings ("Strength" less than 100%) but the result depends on the material and the transients Logic can find in the audio file. Mostly it finds too many in a guitar track and if you decrease the number of transients you easily lose some important bits.
A manual quickie might get you usable results:
Merge all regions on the track when your arrangement is ready. If you played in 4/4 set a flex marker at the first and then at every 4th beat. Not at the bar of the timeline but at the visible peak of the waveform. Pull each marker to its correspondending bar in the timeline. If that is not enough, do the same with every 2nd bar/peak. If this is still not enough and you continue on each beat, it will sound like a machine.
Another technique for simple rhythm tracks is to take a couple of bars, bounce them in place, flex them as good as you can and copy or loop them.
It's like catching the own tail - if you are a good guitarist and able to play a defined rhythm with clear attacks, quantizing may be successful but in this case you'll hardly need it at all. If you cannot play this way and would need quantizing, you make to much noise between the peaks and the quantize function does not work.