True.
Your odds are statistically the exact same, like you said, and your chance of getting a winning roll is the exact same with the different seeds whether or not the outcome is actually going to be different. That's like gambling at another dice site and then being pissed off at that dice site because you didn't gamble on PrimeDice.
True about the odds being the same, but its not the same as if the player chooses to play somewhere else. If YOU choose to play somewhere else its your choice, if pd chooses to change seeds it is not.
There is a somewhat esoteric scenario where the casino could use seed changes to maximise profits. Imagine there would be only one high stakes gambler, that does say 100 rolls on 9900x at 0.00202020 (max bet) a day and would hit it after 2 rolls on the next day. Since the casino can predict the behaviour of the gambler and knows the unhashed seed and so knows that it will hit soon they could change the seeds just in time. They wouldnt know if it hits after a few rolls on the new seed (since client seed can be changed by the user) but its would be a good gamble on behalf of the casino.
I am far from saying something like this is happening, pd has way too many players and those have usually a rather unpredictable behaviour, but since the outcome of a series of rolls is changed due to actions of the casino one could very well argue that this is a little counterproductive on claiming its provably fairness.
Again, I think nobody believes pd does the seed change for reasons like stated above, but its a hypothetical scenario which would likely work on smaller sites with predictable high stakes gamblers.
If that would be the case he sure has a very long time to chase that WIN. Because PD always announces seed change in advance.
Also he can decide not to play anymore once seed changes.
I think this seed change is mostly because Torba will no longer work on Primedice so as a precaution they want to change seeds.
But also because they will be changing up some servers to permanently fix chat lag issue.