You're correct that Boron (coming from Particle, https://www.particle.io/mesh/buy/boron-lte/) is a secure device given that it's supported ARM TrustZone. But IoT security model is far from being complete just by just having that option on your IoT device. Identity and being able to verify the authenticity of the data coming from a particular device is another dimension of security model. These two come "for free" once you're using blockchain on your device as Root of Trust.

Furthermore, it's not just the data on the device which needs to be secure. Data uploaded to a centralized service are inherently unsafe since you're trusting that third party. Decentralized approach (blockchain + IPFS) offers a ticket out of data silos like Amazon, Alibaba, AT&T M2X, IBM Bluemix, Microsoft Azure, Google Cloud, mBed Cloud, and other private clouds and lets device owners to own their own data. We explain this approach in more details in our whitepaper which you can find here: http://www.anyledger.io/.