What I couldn't really understand was this particular reason below. Some of the other reasons did make a little bit more sense, although I didn't really agree with most of them - maybe individually they weren't enough to change his ideas about Twitter, but they combined into one large concern about using it.
This particular reason still has me baffled though...
For one thing, I'm planning on becoming a teacher soon. As such, it's not good to have every single thought you utter out there for the world to see, searchable forever more, by the odd the rogue vexatious parent or and mischievous pupil. I'd rather not comb through everything I've ever said, or run the risk of starting all over and saying one regrettable thing.
It's a different world, this one we're working in now. If you're in the public sector, there are people who are out to get you, to snivel if you do anything other than flog yourself with a cast iron sign saying "sweat of hardworking taxpayers" during a lunchbreak. If you're in education, there are people who might want to see you done down, and could look for any excuse, in or out of the workplace, to do it.
... well OK, you'd want to be careful about what you say, especially if there's a risk that your pupils or colleagues might get wind of it. I'm not convinced that not having a social media account is much protection against vexatious parents or mischievous pupils though. I'm not sure that having a social media account would necessarily help either, beyond letting you put your case across perhaps (useful if you have a fair few supportive followers).
I'm also not sure that a social media account could be entirely neutral in situations where someone's having problems, so I might have to sit on the fence on that one.
You might think that protecting your account could solve a lot of problems. It's a start but it's by no means a guarantee as your friends' responses to you are probably visible, allowing people to surmise what you're up to from what they say to you. I've written about this quite recently (Don't assume that your private Twitter account is all that private).
Possibly one way to go is to use a pseudonymous account and be very careful about who gets to know that it's you - although the content of your tweets can also give you away of course.
I think lots of teachers have found Twitter to be a really useful thing - for sharing resources, community, fun and japes. I'm not a teacher and haven't surveyed their views on it, and I'm sure some teachers haven't any time for Twitter.. but I'm still a wee bit puzzled by the chain of argument given above.
But just to be absolutely clear Steven can do whatever he likes with his own social media accounts and this post is not a criticism of his decision - I just don't understand some of the steps in the reasoning and think bits of them are a wee bit mistaken. I wish him well in his offline life :)