Wang Jian isn't actually proposing rebellion, exactly. Qin's stated goal at this point in time was to reunify the divided empire of the Zhou. In most people's minds, this was probably going to take the form of either feudal overlordship in the form of the ancient Zhou kingship or the latter hegemonic rule of the grand dukes. No one (other than Li Si) could have imagined the centralized Qin empire that would follow, not even Wang Jian. In this context his declaration could still be considered a plan to raise himself a vassal kingdom under the future Qin overlordship that he would help establish.
There was in fact another historical general who did exactly that: Han Xin. In emulation of Wang Jian demanding an expanded fiefdom (and cartloads of money) from a desperate Ying Zheng after Li Xin's defeat in Chu, Han Xin demanded an additional kingdom (Liu Bang already gave him one) to bail out Liu Bang during a crucial moment in the Chu-Han contention. He didn't get to enjoy them for long though.
There was in fact another historical general who did exactly that: Han Xin. In emulation of Wang Jian demanding an expanded fiefdom (and cartloads of money) from a desperate Ying Zheng after Li Xin's defeat in Chu, Han Xin demanded an additional kingdom (Liu Bang already gave him one) to bail out Liu Bang during a crucial moment in the Chu-Han contention. He didn't get to enjoy them for long though.