Once using Multiple Widget with a View: incorrect select list for choosing node type for 'add new node' option

I'm using IEF Multiple widget. I set up a View to provide nodes for the entity reference field.

I get a list of node types in the 'add new node' to choose from. So what type of node I' want to create. This list contains two elements: the one the user must create (no other options) and the node type whoch is the current one (which form I use at the moment.)

Other words: U have an event type and venue_a type and venue_b. I use entity reference to venue_a or venue_b. I use a views to supply the nids. When I'm editing event I see the reference field with an 'add new node' option with a select list with two options: event and venue_b. I presume venue_a and venue_b should be there. Well in my case actually I want to hide venue_b: I want only venue_a to be created (besides venue_a and venue_b are on my View).

My Workaround doesn't work:
As a quick workarround I tried to unset the incorrect node types with hook_form_alter. I gave commmand

unset ($form_state['field_event_venue']['und']['actions']['bundle']['#options']['event'])

which didn't unset the unwanted item. It might be a module wight issue. Have no idea yet.

Any idea how to do a quick workaround before a patch?
(I need my view for node search field. Also I need that user doesn't see any options as no need for overwhelming her. So I cna't change these things)