diaspora* already replaces some characters, so
® just as
I suggest to replace
diaspora\*) if there is no word-character before or after it.
/\W(diaspora)\W/i replace the group by
diaspora\* this case it should catch all occurrences of the word diaspora even at the beginning of sentences and the beginning of lines and even including the hashtag #diaspora and if someone uses “diaspora-protocol”. But it would not affect if someone writes something like “disporians”.
The only downside imho is if someone really really means a diaspora just as in diaspora but this usage is way more unlikely but meaning diaspora*