There is nothing ironic about it. That is Microsoft's M.O.:
Embrace, Extend, Extinguish.
It is a model that has worked for them for years.

Linux is proving to be a hard nut for them to crack but I think they are trying hard to work the same recipe through software patents and prorietary formats ... both of these Nokia has publicly supported in the past and will continue to support via Silverlight. At least they are consistent too.

I personally think that users are better served by open protocols/formats and no patent encumberances on algorithms and business methods. Arguments that Silverlight is more open than Flash are along the same lines as OpenXML is more open than the old MSOffice format. It is a comparison between a maximum security and a regular prison. You'll still be imprisoned and you can still suffer from Stockholm Syndrome.