Perhaps you missed the "Hamas" part? Personally I find it a bit funny when the hostage takers, who've paid nothing for their illegal act, cry and bitch about something and Euros cave in to them. Everybody is playing to the stereotypes.
Hamas might be behind the demands, but the petition is not their doing.
Reading the second article, it seems that there was already a request for a Palestinian footballer to attend the match, so it's not entirely a case of caving in (not to mention that they wanted him not to attend at all).