Start talking about logic gates and flip flops and PLAs and FPGA, maybe even throw in few of the ASICs. If they don't shut up even after that then bring in the big guns and start talking about doping and PN junctions and How BJTs are better than FETs
I've watched few of his videos and they seem OK, but I would never trust a phone like that. I would suggest buy a pixel and flash Graphene OS yourself. It is best for security and privacy.
And as far as Ubuntu touch or any other Linux phone for that. They are currently so bad at security that I wouldn't daily drive them. If you want to play with them or contribute to them then that's OK but don't daily drive them.
Great of you to admit that you were wrong. Also if you want to extend your battery life more try not to let it get below 20% and above 80%. But even without all that a modern cellphone battery should easily last few years