I don't base everything I know off of what a TV
announcer who has seen him maybe one time says.
I've seen him play live and his arm is anything but weak. He's hesitant on his throws and keeps them low many times to avoid INTs. He can wing it and, when allowed to throw downfield, does it well.
If anything, he throws it too hard sometimes, which is why his WRs drop so many balls.
So, I don't think his 'arm strength' is any sort of issue and is something someone said on an internet forum and then gets picked up and spread. He has plenty of 'arm strength' to do what he's asked to do.