Well, for one, going to an Israeli soccer game could be a problem of Moshav Leitzim.
There can also be a problem of Pritzus.
And maybe worse of all is the fact that being that in general Rabbanim are against such things it could be sending his son down on the wrong path...
Um, my Rav (Rav Feivel Cohen Zt"l - not known for being a meikel) told my father that he was mechuyav to take me to a ball game... so I have a pretty good "Mesorah" on this one. (I had begged my father for years to take me, and he didn't want to... until I became a lamdan, and told him on chol hamoed thet he was mechuyav to... to be mekayem vesomach es banav... To which my father said "now thats a tayna, lets ask the Rav if thats true..."...And the rav told my father that is was a good tayna, and he should take me.... though my father said that if we're going to the game lekavod YT, we need to go in bigdei shabbos...

which is how I saw pedros 200th win wearing a black hat, suit and tie in the shea upper deck. He did take me to a couple more games after that.)
There's also the famous video of Rav Zev Leff engrossed in his Gemara as the crowd is celebrating a goal while accompanying his grandsons to a match.