why are all terrorists young muslim men?

They aren't.

- Hammer

One of the most frequent uses of suicide bombings and other tactics
associated with terrorism occurs in Sri Lanka from decidedly
non-Muslim factions:


http://news.bbc.co.uk/1/hi/world/south_asia/780461.stm
Bomb kills Sri Lankan minister

Maybe change that to 'why are all ANNOYING terrorists young muslim men?'

There are Naxelites in India

Supposedly 'Maoists' in Nepal 

Tamil Tiggers (sic) in Ceylon

'Something' in Darfour - and not the hypothetical Jingaweed

- but I guess you are right, they are probably mostly young men.

Just to confirm Pafalafa's comment, since there are both Muslim and
Hindu Tamils in Sri Lanka:
http://www.theaustralian.news.com.au/story/0,20867,20031275-23109,00.html
http://news.bbc.co.uk/1/hi/world/south_asia/2070817.stm

It might be pointed out that young adults anywhere, of any faith or
political persuasion, are more susceptible to idealogical arguments,
be it through indoctrination in their youth (Q'uran schools or Nazi
Hitler Jugend), or as a reaction to their upbringing (the RAF* in
Germany 30 years ago), and maybe in a combination of both for young
Muslims:  indoctrination and a reaction to the westernization in their
countries that has been accepted by their parents.

*RAF: "Red Army Faction"  http://en.wikipedia.org/wiki/Red_Army_Faction

Frde--

Tamil Tiggers? Which publication made that mistake?

The wonderful thing about Tamil Tiggers is
Tamil Tiggers are wonderful things!
Their explosive belts go boom,
their organs go zing ding ping...

Not even all young Muslim terrorists are male:

Russia: Female terrorist disguised as nurse seized at Beslan's hospital
http://www.jihadwatch.org/archives/003061.php 

Western white woman a suicide bomber
http://www.timesonline.co.uk/article/0,,7374-1898856,00.html

Not to mention those who are not Muslim, as mentioned before.