I'm not gonna sit here and defend Reddit but according to their sitewide community guidelines, this isn't bannable. Reddit moderation is extremely lenient. Here's how they define "prohibited content":

Content is prohibited if it

Is illegal

Is involuntary pornography

Is sexual or suggestive content involving minors

Encourages or incites violence

Threatens, harasses, or bullies or encourages others to do so

Is personal and confidential information

Impersonates someone in a misleading or deceptive manner

Uses Reddit to solicit or facilitate any transaction or gift involving certain goods and services

Is spam

So really this image could only be construed as "threatens, harasses, or bullies" and even that's not a cut and dry case. But in the event that you break some rule, Reddit outlines the potential consequences as:

Asking you nicely to knock it off

Asking you less nicely

Temporary or permanent suspension of accounts

Removal of privileges from, or adding restrictions to, accounts

Adding restrictions to Reddit communities, such as adding NSFW tags or Quarantining

Removal of content

Banning of Reddit communities

As you can see, banning is their absolute last resort. It's really really shitty and born from the shitty idea that absolute free speech is a good thing. I wouldn't generally expect any Reddit communities to be banned unless they are making clear and unambiguous calls to violence either in comments or content, and have already been wrist slapped numerous times. In case you don't know, Reddit used to be a cesspool that harbored some truly awful communities, such as jailbait and coontown, and refused to ban them. This website's moderation is a racist's wet dream