My take on this is that I initially loved Maguire's idea of linking social media accounts to a license or passport and hold people accountable for their views, but thinking about it more I think it's actually a bad idea.
First of all, some context about a platform like Twitter, 80% of the content generated on there is done so by less than 20% of the accounts, what that means is that what you're seeing most of the time on twitter is actually written by a minority that doesn't represent the 'world' or 'people in general'. It's a minority, and usually they are the loudest.
Twitter is also a very important platform for breaking stories, whistle-blowing, corruption, etc. This is mostly possible due to the benefit of anonymity. There are positives to allowing people to remain anonymous on social media platforms like Twitter, the problem is you will have trolls, racists, etc that come out and use this to their advantage as well. However, they are, again, a small minority that just happens to be loud. Should that be enough to threaten the positive benefits of keeping that anonymity? That's a question I'm not smart enough to answer, but I'm leaning towards the negative. I think everything should be done to stamp out racism in stadiums, and what's more, it can be done far easier than to try and regulate the internet or its social media. Between cameras, security, feedback from others, it should be possible to imagine not preventing racism, but at least stamping it out and eradicating its perpetrators within days of any incident so that they are not allowed back again not just at their stadium, but any stadiums anywhere. A blacklist that would spread across all major club and international competitions.