Uhm, Glyph, Falconer, I'm the brother in question and I am the GM, not the player. One of the interested players sent me a character concept with both Ware and Astral Hazing. While I was out at a museum I realised Astral Hazing and his low Magic would likely clash, so I called up Conster to ask him to check things for me, hence this topic. I drew similar conclusions but so far the player's disagreeing, partially due to vague language and partially thanks to a discussion on Dump Shock where they never even touched the idea of Magic hitting zero, most likely because it never crossed their mind players might have less than 5 Magic and still take this negative quality.
Thanks for pointing out I technically got a say in the qualities. The player just went Surge on his character concept and I never read into it much so missed that point. Still, I'll leave the choice to him, as long as he keeps possible consequences in mind. The same goes for his recent intent to have both Strength and Charisma on 1, without training in Athletics and Social Skills.
The character concept has high Assessing, Astral Combat and Counterspelling. He's produced as a lab rat and gets away, hence why he's not insane yet. However, the character also has Cyberware and Bioware, decreasing his essence to 3.4. As a result, his Magic goes from 5 to 2 before Astral Hazing, to -2 after.
Here's Astral Hazing's text: "This astral haze affects all attempts to cast magic on, at, or in the vicinity of the character. Whatever the ambient mana conditions are, the character always stands at the heart of a Rating 4 background count (see p. 117, Street Magic) that extends a number of meters from her body equal to her Essence; this background count also impairs her own actions if the character is Awakened."
Italic is what the player stressed as why he reads Astral Hazing as only damaging active spellcasting and not his ability to Counterspell (not Dispel), Banish and Astral Combat. Bold is what I pointed at in return. Page 118 of Street Magic mentions that if your Magic drops to zero due to a Background Count, you lose all Magical Ability. Page 177 of SR4a mentions that the loss of magical ability caused by a Magic of 0 means you can't use any magical skills except as Knowledge skills.
So basically he assumes the short summary line is the only case in which the effect applies, whereas I argue that the more detailed explanation that follows, as well as on Page 118 of Street Magic (and page 177 of SR4a) makes clear what the exact way is that Astral Hazing affects gameplay.
(A similar situation is where the short explanation on Hardened Armor in Immunity to Normal Weapons leads people to argue about whether it works exactly like Hardened Armor or uses the shorter, less detailed, explanation.)
- - -
I'm not sure if a 'temporary' drop in Magic would limit your Initiation grade, by the way. Would that mean a Mage in a Background Count would temporarily lose part of their Initiation if their original Initiation Grade is too close to their Magic? That WOULD be a nice way to counteract people who stick to 6 Magic and initiate a lot to get a lot of metamagic benefits at their disposal. You walk around in the Barrens much? Congrats, you get to turn in your latest initiation benefits and count as a few grades lower for your Masking effect and such.