That is not a sign of being afraid of Arsenal rather the reason given there are valid which is more time to rest and prepare for the Arsenal match. I know the answer would be a no which was what they received because the La Liga matches were already fixed before the champions league matches so you cannot adjust the match for ordinary reason like that since they club is expected to have reserve players that can cover their key players in case they need more time to rest. Real Madrid is in a situation where proper management is needed to being able to play both matches and get good results although the champions league is looking like a lost battle.
I feel Real Madrid is seeking for shifting because they lost 3 zero to Arsenal, if they won Arsenal away they won't have seek for rescheduled of their match in the league. Real Madrid is just frustrated for losing 3 nil to Arsenal, and they want they want to rest and prepare more for come back. But Laliga won't break rules to favor any club. Real Madrid at this point needs to sacrifice on thing to get the other, is either they let go of the league and focus on the champions league. The coach will choose the league over champions league this season, since their chances to beat Arsenal to qualify is very slim. they should channel his energy to the league, Real Madrid must win a major trophy this season, the possibility to win the league and the champions league is possible too.