Well that's good to hear. I mean, we all have our favorite dive ops but we were also all "first timers" with our dive ops at one point. A dive op that would kick new customers/divers off to cater to repeat divers who have "priority" is not going to grow and is, in fact, on the decline even though they may not know it. Regardless of the business anyone may be in, you NEVER EVER turn away a new customer because the competition will make room for them and you'll never see those customers again.
Many years ago I managed a high-end restaurant. There was always a long wait and primarily it was reservations only but we always saved some tables for walk-ins. One night I saw our Maitre'd pocketing a $20 bill from a repeat, well known, customer who didn't make reservations that night and didn't want to wait at the bar. I said nothing to my Maitre'd at the time but upon closing I told him there was no need for him to come back tomorrow and I hoped the $20 from Mr. such and such was worth it. He was well paid but despite my training he chose to ignore the big picture... Probably a host at Applebee's today where he can save on suits, shirts and ties. Greedy idiot.