This is a good point. Block reward is fixed, tx fees are not. Thus, someone can solve blocks at negative cost and bankrupt all other miners, since he can reduce his tx fee to 0.
This is a nonsense statement. It's impossible for any entity to bankrupt all other miners, no matter his transaction fees. Not only would any such miner have to aquire the capital investment in order to build his network to beyond 51%, an uphill battle considering the vast majority of the current running network (now or at any other time) is a sunk cost already paid for; he would also have to compete with the hobbyist miners who benefit from co-generation of waste heat.
I have a GPU based mining rig that I choose not to use, that I can use for space heating in my garage at will. No miner can bankrupt me.
Therefore your "law" is invalid.
That has nothing to do with my Law. That specific vulnerability was something that someone else posted, not me.
If you believe you can use your mining to convert electricity into heat, i hope you live in a very cold climate.