Can non infantry mos wear expert infantry badge?

With few exceptions, no. If you earn the EIB (or CIB) as an infantryman, then you reclass to another MOS, you can still wear it. If you earn the EIB as a non-11 series MOS, then reclass to infantry, you should be eligible to wear it. If you test for it as a non-11 Series, and never reclass to infantry, you can't wear it, even if you complete the testing. However, if you do complete the testing, you should be able to use the points towards promotion.
With few exceptions, no. If you earn the EIB (or CIB) as an infantryman, then you reclass to another MOS, you can still wear it. If you earn the EIB as a non-11 series MOS, then reclass to infantry, you should be eligible to wear it. If you test for it as a non-11 Series, and never reclass to infantry, you can't wear it, even if you complete the testing. However, if you do complete the testing, you should be able to use the points towards promotion.