There is nothing wrong with this and it's about time it happened.
Muslims couldn't have kept themselves isolated, forever.
Although, the only "orthodox" Muslims in the IDF are Bedouins, Druze and Arab Christians are also other Arab communities that serve.
It makes sense only because 15% of Israel is Arab and a country's armed forces have to be an accurate reflection of its people - thus, Arabs being part of their forces.
There are also Ethiopians in their armed forces who are Jews, but still a minority compared to the Russian and Eastern European majority. They are included to reflect the demographic conditions of Israel too (although, it happens, regardless, given that there is mandatory conscription, there).
There are actually more Arabs than 15% if you consider that 50% of Arabs in Jerusalem only carry ID cards and not passports like the 15%. Also, the people in West Bank travel frequently into Israel for employment.
Lastly, the Arab and Israeli issues are of no concern to us.
If Egypt, Turkey and Jordan can have relations with Israel, then, we have absolutely no logic in not doing the same.