Sure assuming that is the code that is used for a given game.  The owner of the game really can do what the want.   They don't even have to provide source.   In any case I bet a great many people are clueless what sha1 is.  That is only one avenue of attack.   The point proof only prove what it was set up for.   If you aren't attacking dice rolls there are many other cheats that can be built in.   Or you don't even have to cheat, you just have to know what will happen from a given computer.  

My point is simple, I don't think a dice game is anymore trustworthy than a Ponzi game.   They all have the same basic problem, that is they have to be trustworthy in the first place.

With a dice game you have the site gaining off of a small edge.   Probably most of these sites are legit.   However if you play it, you will only lose value over time.   The house edge will slowly but surely take everything away from you.   I don't see why that is held up as a shinning example of something fair.