White supremacist anti-Muslim narratives generally refer to Islam as an invading force that isn't just incompatible with Western society but is also an active threat to Western society and cultural norms. In this context, white supremacists have used Crusader-themed imagery and rhetoric, like the Jerusalem Cross, the Knights Templar and "Deus Vult," as dog whistles to promote anti-Muslim hate.

Ah yes, there it is. That does seem to correlate with one of the reddit posts that I saw, but they didn't seem to agree that this symbol had been adopted by contemporary hate groups. They merely indicated that it is controversial due to its association with the crusades. However, that lack of understanding outside of hate groups is the point of using these historical symbols as dog-whistles.