I don't think the timing of the follow-up means anything. Even if it is cancer, you wouldn't need a quick follow up. I had thyroid cancer three years ago and was basically told, "well, it's not going to cause you any trouble in the near future but it's better to deal with it now while you're young and healthy as surgery is a bigger deal as you get older." 

I'd imagine by "it's a long way to wait," they mostly mean it's a long time for you to be worrying about whether it is cancerous or whether it will need to be removed even if benign (like if it could cause problems) or whether you will need the biopsy done again because a lot of thyroid biopsies are inconclusive. Plus, from their point of view, they probably want to get it done. If you need it removed, they probably want to organise for that to be done and if you don't, which is probably the case, they'd want to discharge you and move on to other patients. It sounds like they just don't want to have to keep changing the appointment or for you to be in limbo, wondering about the results for months. Thyroid cancer is very slow-growing so speed is unlikely to be an issue, treatment-wise.