That's odd.
This weekend I noticed that one of the panels in my own home had developed a very quiet 60Hz hum. Of course it was the one mismatched breaker (CH BR in a Siemens panel) I'd noticed years ago when I moved in and occasionally reminded myself I should swap out. But I didn't have a 2-pole Siemens breaker handy. Saturday afternoon, supply houses closed -- off to the big box stores.
Locally, neither the orange store nor the blue store carries any Siemens breakers, much less 2-pole. Tons of Murray breakers on the shelf. This is the exact opposite situation to what I see in other parts of the region when I travel for work. For example in upstate NY you simply cannot find a Murray breaker in the blue store but they have a nice selection of Siemens.
I don't think they have stopped producing Murray. We called their phone support about a month ago to ask whether we could use a Siemens 2-pole AFCI in a Murray panel because our EC on a job said yes, but the inspector was looking at it funny. They said no and helpfully provided the correct Murray part number which we did finally manage to get locally (everyone had claimed they didn't have it). If they've really decided to kill off the Murray name it is very recent!
I think it is just a rumor. You could call them and ask.
The other rumor I would love to clear up is the one about CH stopping all 2-pole AFCI production instead of bringing a 2-pole combination type to market. The last official thing I see on this is a marketing paper from 2009 that says their 2-pole combo AFCI is expected to be on sale late that year. Haven't had a situation arise where I had to know, so I have not tried to call them and be persistent and get an answer from the source -- which is not always possible anyway.