I doubt many people at all are making exactly $65k.
However I also doubt that many CS grads at all are making significantly less than $65k. Those that are making appreciably less than that are almost certainly not working in the field, or they are not working in the US. I wager that the salary distribution of CS grads working in the field in the US is pretty damn tight.
My first programming job in northern VA in 2002 paid 38k and I had a CS degree. I suspect most people make less than 65k because the few at 120+k take many people at 40k to balance things out.
Granted, the job market was crap and I make 6 figures now, but there are still plenty of sub 40k programming jobs out there and people happy to take them.
Your assuming salaries are not inflated and that the ratio of people reporting salaries is constant at all income ranges and the reported numbers are accurate. I doubt any of those are true. So, IMO to observe a 65k median suggests the actual median is below 65k.
PS: Don't forget grad students count as recent CS grads and there generally not making anywhere close to 65K.
This is false.
For example, X% could make exactly 65k and only the lower ((100 - X) / 2)% would make less.
...where X \in (0, 100]