Regardless of whether the methods are queationable, the results are consistent with other studies I've come across on the topic of how stress affects empathy and compassion:
https://greatergood.berkeley.edu/article/item/how_anxiety_re...
https://www.sciencedirect.com/science/article/pii/S240584402...
This is of particular interest to me as I find that I very easily become wrapped up in a sort of protective self-absorption when I get stressed or criticised, making it sometimes impossible to empathize or conduct proper conversations. This in turn has a very negative affect on relationships.
If you're in a similar boat, you might find the practise of compassion-focused mindfulness useful.
https://psychcentral.com/blog/the-practice-of-self-compassio...
The idea is similar to CBT, but with an emphasis on mindfulness and compassion towards oneself and others. I've learned that the "oneself" bit is extremely important. Until you can accept and be gentle on yourself, with all your flaws, you will struggle to be vulnerable around others and thereby cultivate genuine connections.