Oh, sorry, I forgot the most obvious bullet point:

• The IP (design rules etc.) are easier to establish for 40 nm and larger node sizes than for the smaller ones. That's what the article is about.

That means that POET Technologies will be faster to create a 40 nm PDK than to create a PDK for, say, 28 nm. Obviously 40 nm is a good choice because time to market is rather short and the 40 nm PET process brings huge benefits to customers. Smaller ("advanced") node sizes can be done later while revenue is already coming in for 40 nm.