[raleighm]

(Not legal advice.) M&A practitioners aren't paragons of virtue but still it'd usually be considered uncool to go to a former employee years after the fact, ask them to sign a doc to facilitate a deal he'd get no upside from, and not offer to pay his legal fees - especially if he's someone the company let go. It's possible this is just a junior associate at the purchaser's law firm insisting on something technically correct but practically low-risk, getting poor supervision, and your former company not shielding you as they should. It's also possible that if the company tells the purchaser you don't want to sign it, the purchaser just says "ok was worth a shot" and that's it. If the purchaser truly does care, it's the company's problem not yours that the documents you signed years ago weren't different. Not something you should incur time, expenses or risk now to fix for them. An example of risk is the scope of the deed being too broad and covering other projects of yours that should be out of scope. You can say no with a clear conscience. If you feel bad about it, something like the following is a totally fair response: "Sorry I can't be more helpful, but I take legal documents seriously and don't review/sign anything unless it's necessary for something I'm currently working on. It's just a personal policy of mine."