These photos are from a few weeks ago, but I've been too lazy to post them. Here's proof that Harley fits quite well on top of the canned tomatoes, thank you very much!

You can see he's already chewed up the blue box to his left, which has pasta noodles and spitballs inside.
Next is a close up of Harley on the second shelf, considering the best way to destroy the yellow box to his left:

That box has cornbread mix inside; a little sweet for my taste, but not bad for an "instant" mix.
It's a little odd having your meals dictated by the chewing whims of a grey bird, but that's not the only reason we've stopped letting Harley play in the cupboard. He was getting a little
too interested in playing there, if you know what I mean — this was probably related to nesting behavior. A small, enclosed space, things to chew, one of us was always there with him (as a potential mate). Mind you, he exhibits some of these behaviors in other instances, but something about the cupboard was "special," and we decided to stop letting him go inside.
Intense nesting behavior is a little more dangerous for a female bird, since they can start laying eggs, and become unhealthy if they don't have enough nutrients to support egg production. Sometimes the best way to get a female "over" this behavior is to let her sit on the egg(s), or she might continue to lay. Of course, most birds pair up to hatch eggs, and if the female is inclined to sit "tightly" on her eggs, she could get further malnourished if she doesn't have a male to help feed her while she's sitting, or sit on the eggs while she goes off to feed herself.
On the other hand, intense nesting behavior for a male bird is mostly annoying. (I find there are some interesting parallels in human behavior, but that's a different story.) They get territorial, and very aggressive to the people around them — particularly someone who hasn't been chosen as an ideal "mate." Um, that would be me. Go figure. So the cupboard is now off-limits, although occasionally Bruce still lifts Harley on top of the refrigerator. Bruce is very weak.
Apart from general nesting behavior, it seems that birds have different triggers that "turn them on." Most bird behavior specialists warn people not to pet birds anywhere but on their heads, since anywhere lower could be perceived as sexual. Other birds get excited when you touch their feet. Birds have foot fetishes! Who knew?!?
I'm not sure what turns Harley on yet. I'm guessing it's fat chicks.