Scott,
I know how you feel. My last 2 dives for OW certification a year and a half ago were suppossed to be held at Casino Point, and I was so looking forward to going to Catalina for the day and getting to dive again (having already done the first 2 OW dives, I couldn't wait to do it again!). I had been so excited about the trip, but a HUGE storm came through the day before, so we had to cancel. It was awful bcause it ended up being beautiful and sunny the day we were suppossed to go, but since it had rained the night before, conditions were still bad. To make it even worse, we didn't have another time to make the trip over to Catalina (it was towards the end of the year, so with the holidays coming up, scheduling for the class and instructor was tough), so we ended up finising our certification at Corona Del Mar. Talk about 2 extremes - beautiful, Catalina diving, vs. sand and not much else.
I was really disappointed and didn't fully understand at the time why it had to be canceled, but in the year and a half and 75 dives I've had since then, I realize that that was the best decision we could have made. Since then, I've been to the dive park a # of times, so that trip wasn't a once-in-a lifetime thing, just like Shaw's Cove won't be for you. But, diving in unfavorable conditions, especially when you're just learning, could be the end of the lifetime, or at least a not fun time. And, if it makes you feel any better - I had friends who didn't make the same call your instructor did and went diving in Laguna on Sat. Some of them had a very difficult time with the exit (30 minutes to get out due to waves/rocks) and 1 lost fin, so you weren't missing much!
Good luck with finishing up your cert - what shop are you getting certified with?