Good day everyone, I want to keep this question short and simple.
If a project is not active enough on their social media account like Twitter is this a red flag or a reason not to invest in the project.
Depends.
Not all projects use the social media actively but no matter how good the project is, if the management/devs can't spread the word out then it is no good for the investors. So, eventually the project will need to promote their project on the social media, hire shills, do giveaways, create sig camps etc. If they don't do that, the project will die off. There are so many good ideas wasted away like this. Even bitcoin wasn't so popular during its first years.