SO looking at other girls on socail media..

Okay so I know this is going to get a lot of different reactions. He passed out, let his phone die, and didn't put his phone on the charger so I started charging it for him and when I turned it on and unlocked it to make sure his alarms were on I went to close the tabs. Well I saw his Instagram account was stopped on a picture of a female. So me being nosy got on his Instagram account to see if maybe this chick just followed him and he was trying to see if he knew her or if maybe he stopped scrolling at that moment and closed the app unintentionally on her picture. Nope. I found the same picture. That picture was posted by someone who started following him 2 weeks ago and the picture was posted 35 weeks ago. Now he's a new Internet streamer for video games and gets like 5 followers anytime he posts a picture and alot of his followers are gamers, more females than I'd like there to be but its one way he can promote himself. I don't know if I should be mad and call him out on it or just let it go. Now before anyone calls me a hypocrite and says I probably do the same thing I dont. He doesn't want me to have an Instagram because I would "get a lot of attention from guys and want to leave him for one of them". And his reason for having one is because he is a streamer and needs it to promote his channel. The only social media app I have is Facebook. And before anyone says something about me going through his phone in our relationship we both have access to eachothers passwords to apps and he constantly goes through my phone as well.