They wrote about it on their blog in September:
https://fastmail.blog/2018/09/10/acc...sistance-bill/
Nicola Nye, their chief of staff, vented her frustration on Twitter:
https://twitter.com/impishfae/status...37538632736768
You'll find more official replies from Fastmail on Twitter, just search for #aabill or @Fastmail to go through all the responses to questions from various customers.
I'm sure they'll write up something on the blog in due course.
Edit:
This tweet confirms my assumptions above:
https://twitter.com/FastMail/status/1071092471352958977
"Hello! As we blogged in September, we don’t think it affects FastMail services. We will carefully look at the final state in which the bill was passed (including amendments) and issue an update when we've had a chance to get advice."