they aren't arbitrarily locking threads, at least for now.  mods/admins come and go with alarming
frequency, but in the past they've had some who locked threads, and said actions caused a
general uproar, even unto members leaving this site en masse. I daresay they want to avoid
that approach for now.  the offended members always come back, but let them try this more
even-handed approach for now, to see if it works.

the real problem would not be aliens or religion in general, but members attacking a specific
religion. then they'd likely lock such a thread.