This is a void argument. Electrical safety code applies even to lab equipment or equipment used by knowledgeable personal. It really makes no difference, if it is a TV for home use or specialized equipment for electronics lab.
I think one of the applicable limits is 45 °C maximum surface temperature.
That is for example why heatsinks poking outside of enclosures on some power supplies may have additional covers on them to make them inaccessible to the touch.
//EDIT: Okay, maybe my knowledge of this subject is a bit outdated, seems it changed a lot since I have last been interested: Now governed by IEC 60950-1. You can look that one up. Temperatures up to 100 °C seem to be allowed under specific conditions, but the tubes poking through the top of that diy device does not fall under such conditions by any means. a) they are larger than 5cm and b) likely to be touched and finally c) way over 100 deg C, especially the output pentode
So sorry, ain't gonna happen, regardless if it is for "people who know what they are doing", as obviously the do not know, if they are building stuff violating code