Every child is different when it comes to learning a new skill. Some kids never crawl, they'll skip right to pulling up. Or they might sit and pull themselves around with their feet. (I didn't know kids did that until I saw it, but it's almost the funniest thing I've seen...they sit and put their feet out then scoot their butt to their feet...great for those abs.)
sometimes, I think that as 1st time mommies we're so excited to see those firsts we forget that their little minds are absorbing so much in our big world. and sometimes what may take us 2 days to think about, might take them 2 weeks. And they don't multi-task yet.
Plus, sometimes if he decides to cry, it may not be an uncomfortable cry. But a "I know if I do this that mommy-person will come get me and hold me" cry. Thus, harder on you than him. I think it's good to give them some alone time with there toys. it helps them learn to change their surroundings. So when their 4 and can't reach the papertowels, they won't stand there and throw a tantrum until you get it, but they stop and look around and go get there step stool from the bathroom.
If he like sitting, then let him sit. At some point he'll decide he want to change his position. also, he could just have a stubborn streak. The "I am not going to do it while you're watching." my son was like that.
Dad could be right, my kids get overwhelmed once they've pulled out all their toys. So maybe try just a few, then go away. and see if after a while he may decide to get one.
Grabbing with his fingers is a fine motor skill, and those tend to develop later in boys.