Yes, I misread your comment about "weakening Meale's power". Apologies.
You're right that the call on whether to disrupt a ruling-class politician speaking at a labour movement event needs to be judged on a case-by-case basis. For two years running, my union (GMB) has invited senior Lib Dem ministers to address our Congress (Vince Cable last year, Danny Alexander this year). Both times, I've been involved in banner-drop protests during their speeches. This was a tactical call; if the atmosphere at Congress was more militant, more "political", etc., we might have done more. As it was, our feeling was that any attempt to do more (i.e. to heckle disruptively, stage a walkout, etc.) wouldn't have much of a positive impact. It seems to me that in the Nottingham case, the abstract starting point (Alan Meale is a bad guy and shouldn't be speaking at a May Day rally; fine) has not been adequately weighed up against any serious consideration of the impact of the action. Of course, we want to get to a point where ruling-class politicians are not invited to address labour movement events, but in my view the Nottingham action does more to set back the struggle to get there than it does to advance it.
The idea that unorganised workers taking action is "potentially more disruptive" than organised workers seems to me to very much miss the point about how capitalism is disrupted. A train drivers' strike will be massively more "disruptive" to capitalist functioning than, say, a wildcat walkout by some unorganised cleaners in a hospital. That's not a value judgement, it's just a fact about the mechanics of capitalism.
That unorganised workers make up the majority of the working class is obviously just an objective fact. The debate really, then, comes down to how we think revolutionaries - people with a perspective and a programme for working-class power - should focus their time and energy. I think we can do more to relate to and engage with unorganised workers by acting as a lever within the existing labour movement and turning bits of it out towards the kinds of workplaces you're talking about. We (AWL) are already involved in this work on a small scale, for example through our activity in the GMB Southern Region or cleaners' organising projects on London Underground and in the civil service. I think we're the only Trotskyist group to have consistently made the case for radical organising models - see, for example, our promotion of the 'Supersize My Pay' campaign from New Zealand (we were the only UK group to do any serious work around this) and our emphasis on the continuing relevance of 'New Unionism' models. We're also the only Trot group which has actively and consistently supported the IWW's various campaigns (Starbucks and the recent cleaners' struggles), even though we think the IWW is at best limited as an outlet/focus for organising.
So it's really not the case that I'm "less serious" or "less concerned" than you with the struggles of unorganised workers or the need to organise them (/help their self-organisation). It's more that, in terms of the power our class has now, it is derived from the key industrial sectors (e.g. healthcare, transport, education) where organisation is by-and-large stronger. So an orientation to and focus on those sectors and workers' organisation there seems pretty clearly implied.
Please read "Can we build a revolutionary workers' movement?" when you get a chance because I am very interested to know what you make of it. You might also be interested in this pamphlet (it's mainly addressed to activists in the student movement thinking about what to do when they leave college/uni but contains some wider arguments about where revolutionaries should focus their activity): "Change the world - organise at work!".