They don’t believe He died on the cross. They also believe He was a Muslim, and inferior to MoHamHead.
“. . . they [the Jews] said (in boast), ‘We killed Christ Jesus the son of Mary, the Messenger of Allah’ – But they killed him not, nor crucified him, but so it was made to appear to them, and those who differ therein are full of doubts, with no (certain) knowledge, but only conjecture to follow, for of a surety they killed him not – Nay, Allah raised him up unto Himself . . . .”
I'm not Islamic (obviously) or familiar with the official take on this. This seems to be asserting that the Jews claimed to have killed Jesus but it somehow only looked like Jesus was crucified, but Jesus kept on living. The "raised him up" reference in such a context might mean Jesus' birth, or as Islam would see it, Jesus' creation.
So what would seeing a depiction of Jesus on the cross mean to a Muslim referencing this verse? Maybe it would be seen as "what the Jews claimed to have done, but failed to actually do." So this should get them angry once more at Jews perhaps... but at Christians? That isn't logical, but spiritually we know that is happening.