BeerBorg

Would it be a good idea to squeeze flexible plastic bottles to raise the beer level up to the top before securing the cap if bottle carbonating? The theory being that as the bottles re-expand to normal size due to the fermentation in the bottle you are left with only C02 at the top, decreasing any problems with oxidation.
Thanks

I suppose you could, but I would say if using a bottling wand, just fill the bottle right to the top, then when you pull out the wand you will have the right amount of headspace. Unless it's been sitting around for a very long time, there is still CO2 in solution when you are bottling, and while bottling it is being agitated out of solution, so the "top" is pretty much filled with CO2 anyways at that point since it's heavier then air and will displace it. IE doing what you describe you are actually pushing that CO2 out.

I have bottled beer that way and kept it for 2+ years in the bottle without oxidation issues.

I wouldn't worry about it either.
But it might make an interesting experiment. If I did it, I would only squeeze a couple and compare them to the rest.

No harm experimenting but I haven't found oxidation to be a problem when bottling with PETs.