That is great that Sunny had his first greens!

It is good that you were able to test him so often.
If he were my cat, I had hypo supplies on hand, and I knew I was able to stay with him to test him often, then I would feel comfortable with just watching him (no emergency high-carb foods) and seeing what he does, which is what you did! Another thing to note is that the ProZinc Forum isn't as active as the Main Forum, so if you are ever worried about him going low and want some time-sensitive advice then you can get quicker answers there.
You don't have enough days of data to give a good prediction about what will happen if you keep him on that fat 2u. Since you just started him on insulin, are following
Start Low, Go Slow method, and he dropped below 90, he has
earned a dose reduction of 0.25u according to SLGS. See how he does on that, then adjust accordingly. When you get more data on SLGS (at least a month), and are able to continue getting mid-cycle tests day and night, then you could consider switching from SLGS to the Modified ProZinc Method which allows for lower nadirs and lower preshot values. But for this first month, it is best to play it safe and follow the dosing protocol.
If you want to improve the data you collect, try to get a +2 each morning and night (especially the night one). Then, you can look back on this data and see what is number was at +2, and compare it to the current PMPS +2 to see if you can sleep soundly

It's a great way to help predict if he will have an "active cycle" where his BG drops.
Refer to the
hypo emergency page for information about hypo. You will be concerned about both the BG number
and any symptoms he is displaying.
Do you have a hypo-kit set up yet?