I'd say it's possible. That FO probably knew how to work the system a little bit . Even at the craphole that I'm at, I routinely get pay credit about 25-30 more than the block hours (but it comes with effort). In Jan. for example I flew 88.5 hrs and got 121.5 pay credit. So let's say that FO averaged just 110 pay credit for 12 months.. that comes to about 45k, then they probably counted per diem.. which then you get over 50k.
If I can do 110-120 almost every month in this hellhole, I'm sure at a place like ASA and with the shortage, an FO working the system wouldnt have trouble getting at least 120 pay credit every month. It's just that you do have to work at it. for planning purposes though I would just multiply the hourly rate by the monthly guarantee because you just dont know how long you'll be on reserve, what kind of work rules, what kind of line you will fly, how much open time is available, etc.