I very much doubt its engineering roles that are causing the headaches here.Even if Apple could replace everyone immediately losing a flood of engineers would be a legit crisis for the company. It takes months to bring a new engineer up to speed, and losing institutional knowledge can cripple a project. Losing a key person can literally kill a project, I’ve seen it happen.
Engineers would not be working from home ordinarily.
The problems probably stem from clerical staff and sadly by your argument they are far more easily replaced.
I hope they know what they are doing as Apple are being more than generous and are very very likely to call their bluff sometime soon.....