I think Sono’s mom didn’t want him to hide himself the way his father did. I don’t think she wanted him to be “straight”. At least that’s how I interpreted it. The way she asked Yano to help Sono seems like she wants Yano to help Sono be himself more than pretending to please others. I feel it wasn’t fair for her to lean on Sono that way but it’s understandable why she did. I also think that she blamed herself in a way. Hopefully, in the next volumes, we will see Sono and his mom talk things out. I really like how this manga is goofy, angsty, and heartwarming.