Gore DID accept the 2000 election outcome--by allowing the government of FL to proceed in determining the winner.
It was *Bush* who brought the two suits to SC to reject FL outcome. That's why the suits are called BUSH v. Gore and BUSH v. Palm Beach County, with Bush first. (Like how Brown was the one trying to put a stop to the status quo in Brown v. Board of Education.)
Bush and the conservative Supreme Court literally intervened to refuse to allow Florida to recount its votes according to its interpretation of existing law, a decision that Scalia justified in part because he argued that the recount would *cause Bush harm* by "casting a cloud upon what he sees as the legitimacy of his election". Well yes, especially if Florida's electoral process resulted in the outcome that Gore had more votes (as the 2001 consortium of news orgs and statisticians determined he did), it would harm Bush and cast a cloud of non-presidency :)
Bush, conservative elected officials and conservative judges repeatedly rejected the process underway and *imposed* outcomes.
Gore could have brought suit in response in an attempt to reject the outcome, like Bush had multiple times already, but instead conceded, asking private citizens to refrain from pushing to allow Florida to determine the outcome of its election.
So Gore not only accepted the outcome where Bush, conservative elected officials and conservative judges would not, he accepted *another* outcome too, one that the state government of Florida believed prevented it from determining the actual outcome of its election, and which the best review we have determined likely *did* prevent it from determining the will of the voters.
That's double the acceptance of the outcome of most presidential winners or losers!