I don't know that Galloway has been banned from Israel.
But, if he has "his crime" is probably not "organizing a convoy of supplies."
Just google Galloway Israel and you can see that he has a long history of inciting hatred and violence against Israel.
'Jerusalem raped by foreigners'
(VIDEO) British Parliament Member George Galloway calls for action against Israel while praising jihad attacks on coalition forces in Iraq; says United States and Britain are ' terrorists'
Call to violence? - (Video) British Member of Parliament George Galloway has described Jerusalem as being "raped" by foreigners, in a series of speeches delivered on Arab television.
Galloway is leader of the Respect Party, an anti-Iraq war political party based on an alliance between Britain's Socialist Workers Party and the British branch of the Muslim Brotherhood.
The broadcasts, which were translated by the Middle East Media Research Institute, will likely present a challenge to British prime minister Tony Blair, who has vowed to crack down on overt incitement to terrorism in Britain and abroad. Galloway said that Jerusalem and Baghdad were "crying out for help," before praising Iraqi jihad fighters, saying they were "defending the whole Arab world."
http://www.ynetnews.com/articles/0,7340,L-3122173,00.html
Galloway has long been a bitter critic of Israel. He accepted an honorary Palestinian passport from Hamas prime minister Ismail Haniyeh three years ago — after organizing aid trips to Gaza — but was later banned from Egypt. He has reportedly described Jerusalem and Baghdad as being “raped” by “foreigners,” claimed Zionists control the British media, and blamed Israel for the assassination of Lebanese prime minister Rafiq al-Hariri.
NB: ** The UN investigated and found that Hezbollah assassinated Rafiq Al-Hariri.
During a notorious visit to Iraq in 1994, Galloway was filmed telling Hussein, “Sir, I salute your courage, your strength, your indefatigability.”
http://www.timesofisrael.com/anti-israel-politician-galloway-wins-shock-return-to-uk-parliament/
On May 23, 2008 Finkelstein was denied entry to Israel, according to unnamed Shin Bet security officials, because "of suspicions involving hostile elements in Lebanon" and that he "did not give a full accounting to interrogators with regard to these suspicions." Finkelstein had previously visited south Lebanon and met with Lebanese families during the 2006 Lebanon War.[59] He was banned from entering Israel for 10 years.[60][61] http://en.wikipedia.org/wiki/Norman_Finkelstein#Denied_entry_to_Israel_in_2008
^ “Israel blocks professor from entering, citing Hezbollah ties” International Herald Tribune 24 May 2008. Accessed 24 May 2008