You don't know how much the money was, and I'm not sure you would if you were in his shoes. If you were in his shoes, you would believe you were owed £3million.
If you were owed £3million by someone, and they went "err, would you take 10% of that?" you'd tell them to eff right off, wouldn't...
Quite. NO ONE HERE knows EXACTLY what happened in the final 6 months of Gus' tenure, to make him do a complete U-turn from LOVING his job to being very unattached to it. Clearly things happened during that time that meant the relationship was unworkable.
Obviously IF he's sure he did nothing wrong, then an offer of anything below a million would've been seen as an insult, and rightly turned down. The club signed him on a contract, and that contract represents a promise to pay that £3m or so.