When you mix your audience and an opposing audience on Twitter, expect a garbage fire to erupt outside your door.
This is not strictly a bad idea. It does let you communicate with a new audience in a very limited capacity, but that's about it. Here are the technical parts to be aware of:
- Most users don't interact much with the hashtag itself.
- Most of your interactions are likely coming from your followers, and retweets off your followers.
- This serves only to entrench an echo chamber around your content. That echo chamber serves you in a practical way, drawing a popular audience to your article.
- Quarantining content users don't want to see is effectively a tenet of social media design at this point. Systematic bias works against you.
- However, including a hashtag clearly signals to your readers what you're talking about.
- The extent to which you as a journalist feel you need to report your ideas to the "opposed" audience is also relevant.
Generally speaking, in the framework I'll use here, there are three primary audiences at work here: yours, followers of your actively-retweeting users, and the direct consumers of the hashtag. The first two are your own ideas reflected back to you. You won't change their minds; you are purely an informational source to them. Even when your piece is an argument and not just reporting facts, your readers already agree - they're just learning how and what to argue.
Direct consumers of the hashtag are going to fall into two subgroups: very interested parties, and newcomers to the topic. Newcomers will likely be there to learn what's happening, and offering a counterpoint piece could be one piece in that. In practice, though, this group is small - in the current climate, Twitter isn't really a place people go to learn constructively about something. It's likely to be swamped by interested parties, people who are going to monitor the topic. And since you're posting in a controversial area, these people don't have your best interests in mind.
(The third group comprises all reactionaries. These people will come out of the woodwork to attack you if you post certain content. Whether this happens for you depends a lot on what you're writing about, and whether reactionaries are focused on it in the moment. If the answer is yes, consider this risk.)
Under this framework, you are bringing two audiences together: one audience is reading your tweets for informational purposes, to learn and understand; the second audience is there to dispute you. Notice that neither of the dominant groups is here to have their minds changed. In addition to the caustic debate style Twitter loves, those two groups when mixed are pyrophoric, and you may end up with a garbage fire.
...or you might not. This question is in the realm of what may happen, and not what will. If this doesn't fit, and you think you stand a chance of changing the topic, or drawing new people into rethinking their undeveloped position... go for it. It may be worth a shot.