I’m a bit surprised they are reporting on this now. We’ve known for years that bacteria can survive in low oxygen environments like the urethral tract of men and women. Studies at the time were looking at sex between men and women. I wouldn’t be surprised if similar discoveries were made for same sex couples across multiple gender pairings.

https://microbiomepost.com/vaginal-sex-can-change-the-urinary-tract-microbiota-of-healthy-men/

Most men had a simple urethral microbiota, dominated by Streptococcus and Corynebacterium species. Some men also had a more complex secondary microbiota composed of microbes that are typically found in the vagina and are associated with vaginal disease. The likelihood of detecting these bacteria, which include Gardnerella vaginalis, was elevated in men who reported having vaginal sex. Vagina-associated bacteria remained detectable in men for at least two months after vaginal sex