By Sheila Dang (Reuters) -Mere hours after Elon Musk kicked off a new era at Twitter Inc, the billionaire owner was deluged with pleas and demands from banned account holders and world leaders. The flood of requests underscore the challenge the CEO of electric car maker Tesla Inc faces, balancing a promise to restore free speech while preventing the platform from descending into a “hellscape,” as he had vowed in an open letter to advertisers on Thursday. Former U.S. President Donald Trump, who was permanently banned from Twitter over accusations of inciting violence after the Jan. 6, 2021 capi…