The anti-gunners are bullies.
Trust me, I know from bully.
An important part of your response to bullying is that it be immediate.
If you back off and give them some time they come back worse and if you respond in between attacks they point out YOUR bullying.
The silence from the NRA is giving them this time.
Being respectful to the dead is nice, but we didn't break the moment, they did. Being silent after that is taken as acquiescing to their position.
I know we all want to do the right thing, but we also don't want to be the nice guy who finishes last.