I think some of this criticism is based on something seeming more unusual than it actually is, just as we saw with the judge in the trial, people were making criticisms of this seemingly crazy judge on the basis of... well apparently no experience with crazy judges - just an expectation of how judges should behave from TV/films etc.. whereas actual US lawyers on social media were quick to shoot down lots of the criticism.
Similarly, with this politician (not sure why it's being discussed in this thread but meh, I guess no relevant updates to discuss at the moment), people (whether Europeans or urban Americans living on either coast) might not be as aware that it is quite standard behaviour by some Republicans/gun owners in the US to pose with guns like that. The family Christmas card with guns thing has been done before, including by politicians - some gun clubs over there have been reported to have had events where you can pose with guns with Santa etc..
This isn't the first time a politician has done it either - obviously, they expect it to be polarising, generate outrage from some etc.. and that is part of the point but as far as the timing is concerned, it is December, I doubt much thought was paid to any school shooting etc..
Here is another example from a few years ago:
The toddlers dont appear to have guns, I call fake.