Ofc, there is no hard evidence and the article does a lot of "supposing". BUT if we just take a pretty logical pathway:
1. This is technically legal.
2. They have the equipment to do so.
3. In theory it is pretty "safe".
4. The reported "gains" going off the few studies out there (see below) would be something like 4% increase in V02 Max... and that is doing it in a pretty unsophisticated way given how it was achieved in this study... cycling teams have more money and specialist knowledge, and I am sure could maximise results due to this. And these people are not high-end athletes... we generally know from other methods (EPO) that athletes often respond better to such things and have higher gains... the few studies on EPO seemed to show a ~5-7% increase in V02 max for the normal person vs 10-15% for athletes.
5. Xenon and Argon did similar... seemingly to a lesser effect going off the reported gains... and both were widely used in athletics for 10 years, and almost certainly cycling, before both being banned in 2014. And no-one seemingly had an issue doing it before it was banned.
So, we have a circumstance where:
Teams led by people who have been involved in doping their whole careers.
Have a legal avenue, that is quite safe, with the equipment necessary.
To increase their cyclists V02 max by at very least 4% within a few weeks with no extra effort (which is incredible in itself but would probably be more if pro teams were doing this!).
And they would choose not to do it... for what? To protect the integrity of the sport? But they would not be breaking any actual rules? Yeh... I cannot do the mental gymnastics required to believe it is not being done.
(
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6562501/)