I sympathise with the OP because at some point everyone becomes too old to deal with the headaches of running a community. I have no opposition to their choice to shut down the forum. I just don't believe liability as a result of the new bill is the reason.
there's never been an instance of any of the proclaimed things that this act protects [...] people from, so he should be safe, right?
but despite this, he is already being attacked, and those attacks will not just continue but they are likely to increase because the attack surface has become larger.