Extremely tough call. I have a day job, but for a number of years I did artwork freelance full-time professionally, and I still take on projects consistently. Having a day job affords me to only take on projects that I want to. When I did not have that and freelanced entirely, I could not afford to ever be picky.
I think this is less about "passion" and more about what you personally can handle. Will you be okay working on art that you don't want to, that is truly a job, without the "fun" aspects of it? Have you done some small freelance projects to see how you fare? Some people have a very hard time treating art like a job, and can only draw when they are inspired or in the mood. That's important to know who you are and where you fall on that scale.
I've worked on projects I've loved, and projects I've been very so-so about. All of them still turn into jobs that I have to force myself to put in hours on every day. Even if you do love art, you will probably not love every project every moment. A job is still a job.
I'd say that companies look for someone "passionate" about their project just like a job application says "passionate" about their business... like they want you to put in extra work for no extra pay because you're so into it! Hah! So I'd just smile and nod through that. You don't have to love every second for the job to be a good fit. If there are interesting things in the script or subject matter you feel you'll be well suited for, or things you'd like to learn to do, that's important, even if it's something you'd not choose for yourself personally.
Do you want to work on any project, just to be a fulltime artist? Or do you really only want to work on things you truly enjoy? There's no one right way to do it or right answer. Just whatever is the best fit for you. If you want your portfolio going forward to only reflect what you like, then work on only projects that really speak to you. If you want your foot in the door and to prove you can work professionally, go for it! Just be sure they're legitimate and get a contract up front for how payment and possible early cancelation will go.
Best of luck, and congratulations on the job offer, whether you take it or not, that's a great sign
even if you turn this one down, I'm sure more will come your way!