Hmmm, good question!
After some thought, in this case I think I'd recommend holding the 0.75U dose for a little longer. The caveat is that, yes, technically under SLGS a number under 90 means an automatic reduction, regardless of when the last reduction happened. So this advice should be taken as a one-off and just based on Quincy's individual situation, not a general recommendation.
My reasoning: looking at Quincy's recent spreadsheet, he looked like he needed a bit more juice after he'd been on 1.0U for over a week. Under SLGS, with nadirs above 150, the recommendation would be to have increased to 1.25U last week. With that missed increase, your excellent testing frequency, and with the fact that he just barely dropped under 90 today, I think there's an argument to be made to be a little more aggressive than the method on this occasion.
Can I ask why you are doing SLGS rather than TR? You test enough for TR, and it allows you to be a little more proactive on dosing than SLGS.