Can you still Zipline if you are older. (60's) and not very physically strong?

Yes you can it's not about the age it's about the wait. Then you have a guide in the front and a guide in the bag to help you if you get stuck in between. But usually that never happens.

Absolutely I was 65 had no problem, went twice so far! Amazing!!!

The weight limit is 270 pounds

I am not sure. There was an older couple but seemed very active when I went.

Yes, you absolutely can! I know people that went and they are 70-75 and are not super fit and active.