I know several trans ancap individuals online now, all of whom are incredible people. I suspect the ancap/voluntaryists who are logically consistent are not downvoting the LGBT tag.

However, it is very important to note steemit is not 100% voluntaryist. There are a number of other individuals, ideologies, and concepts out on Steemit. Although we are more of a majority on this platform than others, that fact doesn't imply that some content providers a) have/do not have an inherent bias against the LGBT community, or b) that all members of steemit are ancap.

That said, it might not be the tag itself that is getting downvoted, but the content posted to it. So far, what I have seen with downvoting, and from my own usage of it, it tends to be used to express discontent with an individual's content, not their subgroup classification. This may be the core issue, and the emergent problem from it is the downvoting of a tag collectively.

Someone would need to analyse the content associated to that tag to see if the posts themselves are consistent and logical, and in line with voluntaryist principles. If they are, and they are getting downvoted, then the LGBT tag being the cause of the downvoting is highly plausible, and some logical arguments need to be put to those who are doing the downvoting itself.

However, if members of any group are making claims they deserve X more than other groups, because of their group status, that is collectivism, the antithesis of anarchocaptialism. Even I, as open minded & committed to spreading this philosophical view around as I am, would downvote such claims, regardless of the group they are part of.

One final point - Steemit has a very heavy following in the developing world, especially against that specific tag (from a cursory glance at the "hot" topics on it). This region is not as open to certain lifestyles being permissible, just as most individuals in society cannot comprehend life without the state.

My advice is to downvote responses or content which uses fallacious reasoning to justify any negative claims against that community. Use the tools to hand to help anarchically moderate opinion on the network. If most people agree with your concerns, then it will work.