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Circuit doesn't look that bad to me, for a mass-manufactured product is a good starting point. Having said that, in standard form if it was a commercial product it'd probably fail EMC test. It would need to be developed a bit more.
I like the way they block the sale of the hex code for it. Prevents people from building them too easily. If someone is prepared to write the code for it, hopefully will be committed enough to realise how potentially lethally dangerous a circuit like this is for a home electronics project. There's no easy way to test it, if you connect a scope to it: bang!, if you develop the code with a PIC emulator: bang! if you touch it with soldering iron: bang! if you touch it: ouch! , or ouch!, bump! (as you fall to the ground unconscious)
Bit of an investment is an Isolating Transformer. Years ago when I worked on the bench, the 'done thing' then by people was disconnect the earth off the scope. Bit silly, you got a shock off the scope each time you touched it . We're 240 V mains here in UK, that's nearly 400 V peak, nearly 1/2 a kV! A battery powered plastic scope is another way. Yes a proper isolating transformer prevents bang! when connecting scope, but I think it gives one a false sense of security, but that's me.
Horses for courses. Most of this circuit was likely lifted from a mass-manufactured mains-powered product, where cost savings have to be made to stay competitive, or else fall by the wayside. No consumer wants to pay more for a product if there's a cheaper sold one elsewhere that does the same job, consumer isn't impressed by things he doesn't know or care about. I've seen these transformerless non-isolated power supplies often, this is about average for them.
But to use this as a circuit for a home hobbiest project, or even for industrial electronics product I'm with yourself, nigel and hero about it.
If you really must make a controller involving mains power line voltage, then choose a circuit that uses an Opto-Isolator between the mains voltage and the rest of the controller. Ensure all the mains voltage stuff is insulated and touch-proof, right up to the opto-isolator. Remember, you're the person responsible for your safety, and you need to be aware of what the risks are and how you address them. Don't forget Darwin's Law of natural selection operates quite well here!