Note -- Pagan: any religion that developed in a place where there is not a lot of sand.
To the ACLU, the cross poses a threat because it represents truth that is not man-made.
The Roman Goddess is non-threatening as far as the Left is concerned because they think that it represents moral relativism. Nothing could be further from the truth.
Most of those who are practicing revived European religions today are not being very fastidious about it -- they are 'cafeteria' worshippers. If they did their research, they would find that the religions that originated in pre-Christian Europe [or likewise in Asia, Africa or the Americas for that matter] were quite strict, objectively based [the truth comes from the Divine, not man] and required considerable sacrifice.
In many cases, there was a type of monastic system wherein -- starting in childhood -- people would spend years learning the [often highly complex] theology, the healing arts [many of which were quite effective], practical handicrafts, the ways of the local living creatures, etc. These people were as devout in their religion as any. They considered Life to be a blessing and held that there was order and justice in the universe due to a Divine Plan.
Most of today's neo-nature religion practitioners couldn't be bothered. Instead they just get together and play at the the practice, only doing the parts that are fun and don't require much commitment or effort.
That is why the ACLU is not attacking the Roman Goddess. In fact, the ACLU clearly advocates choosing one religious symbol over another, which is clearly prohibited in the First Amendment. I am offended by this as an American -- even though my own theology is non-Abrahamist -- because the government has no business promoting or prohibiting any given religion.
...and those of you who wish to berate me about how every religion that did not originate in the Middle East is false are free to look here for my position on these matters:
Theological ExclusivismI see the same thing with many Western "Buddhists." If they really practiced Buddhism they would quickly learn that their aversion to what they term "the judgemental nature of Judeo-Christian faith" would turn to abject infinite terror upon learning the fate which probably awaits them according to the Buddhist scriptures!