You can't force a truce with a nation that you are sieging or is sieging you.

I think he means that a truce can be forced right before the siege starts

I don't understand the downside of that. Can you explain? I only see it as a benefit: the occupied nation achieves its goal of being unoccupied, since by forcing a truce the occupier will be forced to release your towns. This makes a revolt unnecessary.

the truce will keep the nation from fighting in sieges for a month normally but if someone starts the truce right before the revolt window opens for example i got sieged on 14th June
The occupying nation would do the Forced truce command on 27th June , which means we cant counter siege until 9th of July if you account the peace weeks and 1 Month truce

I see the down side here is you can effectively make a nation not able to start sieges against each other for 1 month, 2 weeks or even 1 month, 3 weeks

Is that necessarily a bad thing in every case? A lot of people complain about an endless siege/counter-siege cycle.

Its not just sieges but pvp regions and movecraft regions that you cant participate in the reason ppl complain about endless sieges is cause nations doesent really have a replayability of sorts everything is just unfun grinding for a siege cause theres not mutch else to do

if we get forced to stay 1 month doing nothing what do you expect , we would want to counter siege someone as soon as we get unoccupied , not be occupied for 21 days then get a forced truce right as we revolt , yes we do get unoccupied but still 1 month without counter sieging , and if that nation sieges regions we cant help our allies too .