I would think it would be very unwise though I obviously do not know the personalities involved.
For example, if your friend asked for 5K and the current employer thinks this is greedy, then would that not put the new job at risk given that the current employer arranged it?
The redundancy is not necessarily a huge figure as your friend is entitled to 2 weeks per year of service + 1 additional week which is capped at 600 euro per week, ie 21 weeks x 600 = 12,600.
If I was the employer and I was asked for 5k-10k in this circumstance then I would simply make your friend redundant if I do have a valid need to reduce my costs to survive.
It seems to me that the employer is acting well beyond his call of duty in sourcing a new job through a contact of his. However, I am only basing this on the information provided in your post.