I didn't perceive it as particularly insulting to homeless people. The issue I take with it is that the homeless are even mentioned at all and that they're presented as something to fear. https://www.psychologytoday.com/us/basics/microaggression. It's a small thing, but I think all works of art&media can spread positivity or negativity, and I think this is unnecessary negativity.
It seems unnecessary since to me, the goal of the narrative in that section is to show the personalities of the two; Haruka is more timid and Shiina is more bold. This narrative goal can be achieved without associating a negative emotion to people who are down on their luck, even if that negative emotion is founded in real experiences. It would be different if the section also offered some social commentary, but that's not the case.
You're welcome to stick to your artistic vision, but I think some small changes to that section would improve it. Perhaps even just remove "homeless" and keep "scroungers". The groups don't fully overlap; there are scroungers with homes.
Again, thanks for your work! Yuri is a niche genre and I'm glad you're contributing to the space.