point to point wiring is a hell of alot safer than using perfboard in a valve kit.
in fact if I was going to make something with a valve in it (and that isn't going to happen anytime soon) I would use point to point, PCBs in general aren't that good for them because they tend to warp (as I've seen in a few of my marshall amps)
that amp on instructables looks bloody ridiculous, not unsafe just pointless. use something like a STK4152 or even a TDA2030 and make a decent solid state amp!
you should never assume anything with a kit business, even on the last amp hour D & C were talking about the makerbot where the owner said he was constantly having to help out people who just shouldn't be building a kit like that. people tend to just see the price tag not the potential issues, they also think they can follow instructions until they see that schematic.
I'm not normally a safety conscious type, I just have certain thresholds and pissing about with 400 volts is one of them, I know it hasn't been confirmed the voltage used but then there is absolutely no information about it on the net so 400volts is a guess.
as for buying scissors and electrical cord at the same time, I went into a store and bought these baby's