OP - did you ask her why she keeps any food in the fridge which she later wants to eat warm?!
FFS - there is a reason that babies who are FF have more D&V and why thousand of babies in the thirld world die due to unsafe FF practices.
However, having said that and looking at the science this may not be as bad as it initially seems:
If you look at these slides from a WHO/FSA meeting - especially page 15 - you will see a range of scenarios of making up formula (contaning the nasty bacteria) with different temps and holding times.
The baseline scenario was making up with water which is 30 degrees and feeding immediately. In all cases using water at 70 degrees led to a reduction in risk of more than 100,000 times - this was regardless of the time between preparation and feeding.
This was also the case for "No refridgeration, re-warming and an extended holding time" - however you'd need to be bloody sure that the water was 70 degrees because in that scenario with water which was 50 degrees the risk was increased 97 times compared with the base line.
OP - are you aware if she is definitely using water which is at least 70 degrees - this means 1 litre of water boiled and left for 30 minutes.
So those who are horrified by this but not using water which is 70 degress may be being more risky than OP's friend.
Also that experiment relates to the Enterobacter sakazakii bacteria and not any other bacteria which may be in the bottles etc. Just to be clear I am not recommending the approach!
Dept of Health/Food Standards Agency guidelines for HCPs.
Very well worth a read because it explains how to make the bottles if you can't make them fresh each time - still using water at 70 degrees but rapidly cooling and storing in the fridge. Also keeping a flask of hot water.
PassMeTheKleenex - the above link will answer your question.
Also the WHO guidelines.