The company are following the procedures laid out by head office, and this applies equally to every member of staff.
If you have time off sick then it is counted as a percentage of your working week. So as he only works 8 hours, if he has a day off sick then his % is much higher compared to someone who who works 24 hours and has a day off sick.
Everyone who has a high % usually has to see a manager about their attendance, and he will probalbly be given a verbal warning.
This is normal, and happens to a lot of the staff.
I dont believe they can sack him without going through verbal then a written warning.
Hopefully he has had his share of the bugs going around, and will be ok from on.