It won't be easier for kids to get it
First, it may seem easier for kids to get marijuana when it is legal for adults, but the opposite is true. Polls show that kids claim it is easier to get marijuana than alcohol or tobacco. This is because when it is sold on the black market, the dealer doesn't check ID.
Second, his opinion regarding cannabis as a "gateway drug" is mere fallacy. It's obvious that he understands heroin, cocaine and meth are much more dangerous substances than cannabis, and I agree, especially considering that cannabis itself is non-addictive and non-lethal. It is possible to become psychologically addicted, but then again, you can become psychologically addicted to anything. Why then, is cannabis a schedule 1 narcotic alongside heroin, if it is indeed a gateway drug? With that logic, heroin must be a gateway drug too.
Lastly, he mentions that this pot is different than what my contemporaries were smoking in the 60s. The notion that the today's cannabis has somehow genetically evolved to become a much more dangerous (or lethal) substance in the span of 50 years is simply nonsensical. Cannabis has no realistic lethal dose. Simply put, I would be more concerned with minors obtaining a dangerous drug, (like alcohol) rather than cannabis. Cannabis is safer than alcohol.