Good. It probably wasn’t enough insulin, but some is better than none. I would have probably said to do something similar given the testing constraints.
I see you gave high carb food when he was at 70 at +8. That’s not a number that warrants HC food to be given. With your ReliOn meter, you should save HC for when he drops below 50. A small snack of his regular LC food would have been appropriate if you were concerned, then get another test in 30 minutes. A 70 at +8 is absolutely fantastic and means he was getting great duration of his ProZinc. We don’t want to hijack a nice cycle like that.
What happened with the visit to the vet for straining to urinate? Is he back to normal now? Poor boy!