I disagree, it's a very apt description of an increasingly common phenomena online. When one's need to signal group membership outweighs their personal feelings regarding the issue at hand, that's virtue signalling. With the balkanization of online communities to being hyper-focused, and actively exclusionary of those with slightly different beliefs, virtue signalling becomes an important component of becoming and staying a member in good standing. Online political forums are stark examples of this.

Sort of. My understanding is that it means "declaring your (virtuous) opposition to <bad thing X>, regardless of whether <current topic Y> is actually an instance of X or whether Y is actually harmful."

On the right, it might be: murder is bad, therefore I oppose abortion.

On the left: gay marriage is good, and opposition to it is homophobia, therefore Brandon Eich should be fired.

When the link between X and Y is too specious, it implies the speaker's primary goal is to show virtue by opposing X, rather than any real concern they have about Y.