Well, he said it:

Maria Watches Over Us strikes me as social satire. We have here a story about privileged young ladies who spend their time worrying themselves sick over problems that could not be more inconsequential. Furthermore they all act sort of gay. []

So true. Although, as for the lesbian part, it varied quite a lot in intensity from a pair to pair, with the main duo being mercifuly left in peace. Jonathan decided to paint (or smear) them all with the same brush.

INSIGNIFICANT UPDATE: Jonathan writes that "none of the characters seem interested in boys", and that Sachiko treats Suguru "coldly". Contrary to him, my impression was that Sachiko loved Suguru despite him being an undeserving jerk who abused her and her feelings. There was some explicit dialogue about it at the end of ep.2 or about that. The anime never returns to this important topic after the conclusion of the mini-arc, despite Sachiko being the second most important character. Maybe the pressure from the yuri fans, who were in denial...