Well, for one thing, he cannot be out on the porch on its own so, unless you live in the porch, he needs to be brought inside where there is people. He'll never get over his fear of people if he is not inured to them and he can't get used to something he sees only sporadically. He needs lots of exposure - always keeping the 'safe' distance and not staring at him but he needs to see and hear people living with him. They are highly social birds and isolating him is only going to make things worse because being alone, to a parrot, means being vulnerable and unsafe which, in turn, causes anxiety and stress.
Now, you NEED to change his diet. I am sorry but there is no two ways about it. He can't be free-fed seeds - they will destroy his liver and kidneys, clog his arteries, create uric acid crystals in his kidneys and joints, make him hormonal, etc. Parrots are not seed eaters. They are eaters of fresh plant material and, although one could say that seeds are plant material, it's a fact that seeds are not found in nature all year round and that the ones that are found are not dry but what we call 'green' seeds (seeds inside the fruit). Plants bloom, fruit and seed only during the growing season, never during the resting season.
It's not hard at all to switch them as long as you prepare the right dish and time it correctly. Let me explain. Grains are not seeds (they are actually the fruit of the plant) but they do resemble seeds A LOT so we use their natural inclination to eat seeds (parrots love seeds and are hardwired to gorge on them precisely because they are only found during their breeding season and because they are high protein - without which they could not breed) to get them to eat a healthier fare. I've been using and recommending gloop for many years because, in my personal opinion, it's the healthiest food you can give them - and also the easiest to switch them to
You can look at all the different recipes of gloop in the diet section but, basically, it's just whole grains cooked al dente, mixed with some pulses (like lentils) thoroughly cooked (you can't half-cook beans) and mixed with frozen veggies (frozen produce is the most nutritious, more than fresh or canned). You cook the grains, allow them to cool, mix them with the frozen veggies (without thawing them), split into daily portions (some people that have only one or two birds use ice cube trays) and frozen. Every night, you take out one portion and allow it to thaw overnight so it's ready to serve at dawn. Sometimes it works best when you put it on a white paper plate at the bottom of the cage, sometimes they like it in their food bowl - you will have to see which he likes best so try both and see what happens. Now comes the 'timing' part of it. Birds are their hungriest in the morning so what we do is take out the leftover dinner (which should be a portion just the tiniest bit bigger than what their crop would hold) once the bird is asleep at night and wait for one hour after the first light in the sky to serve them breakfast so he is good and hungry for it (as time goes by and he gets used to eating his gloop, you can serve it a bit sooner). Start by making an all grain gloop (with no veggies) and mix the tiniest sprinkle of a budgie seed mix into it. He might not eat it at all the first day but, on the second day, he will start to pick the seeds out and in a couple more days, he will start eating the grains (you will know when you see empty white 'skins' laying around or in his food bowl). Once he is eating the grains regularly, start adding veggies starting with corn (they all LOVE corn with a passion and it's always the very first thing they pick from the gloop), once he is eating the corn regularly, add peas, then diced carrots (I use the peas and carrots frozen bags and, if you do too, just add them both together), then chopped broccoli (make sure it's 'chopped' and not 'cuts' or 'florets' because they pick the bigger pieces and throw them out but they will eat the chopped).
Diet has a lot to do with mood and even more with health so it's imperative to feed them right.