Career advice: Post-doc away from my primary interest, or not
The most important thing is to evaluate if you will be able to keep a steady output of papers during this post-doc, if you can't hit the ground running than you will lose time to get comfortable with new material, two years go by very quickly. Also you should consider if in your country a post-doc in a different place is valuable experience to get tenure. You are the only one that can decide.