I was browsing some old threads and I wanted to see the results of a poll.

Too bad you can't.
If you try to vote you get this message:

Polling is disabled for topics that have not had any new posts in 3 months.

This is understandable, the problem is that the option "View Results (Null Vote)" is considered the same as voting on the poll and you get the same message.
Basically the only way to see the results of old polls is to have expressed a vote or clicked on "View Results (Null Vote)" as it was still active.

It would be nice for the View Results option to always be available, or for the poll results to just be shown when voting is disabled.