Really? Actually, if you look at any numbers, it doesn’t seem like bad advice at all, and I doubt there will be much issue with holding threat either.
Although, I’d personally go with Thunder Clap for dmg mitigation over threat, this is not a bad opener at all, imo.
A lot of people spec deep Arms while leveling, some prefer Fury, and still some go deep prot. There are trade offs to each decision, and ultimately it’s up to the individual, but all choices are viable while leveling, though I’d say going deep Prot early will likely push you to run more dungeons, or party more often than you may otherwise (not that that’s a bad thing).
I put together a low level warrior tanking guide that may be of some interest, and I’d love some feedback on. I’ll be updating it for higher level stuff shortly.
There are some sections on macros as well, which I find helpful. I’m a big fan of understanding the reasons behind the advice, and digging into how to know how to know for oneself, so I also recommend having a look at Magey’s WIKI for Threat Mechanics: https://github.com/magey/classic-warrior/wiki/Threat-Mechanics
It can be very helpful to understand precisely how threat is generated, and which skills to use in which situations.
One such skill is Battle Shout, and having an understanding how its multiplier works on party members (and their pets) who are currently on the threat table of a mob, makes it clear when and how it can be beneficial for keeping aggro on mobs over AoE damage dealers.