can I use Italian Meringue buttercream for a frozen buttercream transfer?

I would think it would work.

I don't think freezing would be any problem at all with all that butter, I personally would try a small test FBCT just to see how the colors with the icing would work when thawing.

Just wanted to add, that you probably don't even have to freeze a FBCT made with this icing as butter is so solid in a refrigerated state