I've never been asked to sign a non-disparagement clause, in a couple large companies and a few startups. I've seen a few, which were time-limited.
In a merger situation (or any other where you're already employed), passive chicken is sometimes effective. Like, say that:
1. You love the company and can't imagine ever "disparaging" it, in the common English sense of the word;
2. but you're not sure what their clause actually means legally, since you're not a lawyer, and you are always very careful to abide by the contracts you sign;
3. so it really would be simpler to remove that language.
Then just keep delaying, and see what happens. They'll either revise the contract, or forget about it entirely, or start talking about a termination date.
In a merger situation (or any other where you're already employed), passive chicken is sometimes effective. Like, say that:
1. You love the company and can't imagine ever "disparaging" it, in the common English sense of the word;
2. but you're not sure what their clause actually means legally, since you're not a lawyer, and you are always very careful to abide by the contracts you sign;
3. so it really would be simpler to remove that language.
Then just keep delaying, and see what happens. They'll either revise the contract, or forget about it entirely, or start talking about a termination date.