=Your argument gives total freedom to these manipulators.
Freedom is moral, taking away freedom is immoral.
They're stealing miners hard earned BTC's very subtly. Thats it.
I hate it when people redefine "stealing."
If you have a nugget of iron, and I take it from you without your consent, that's stealing.
If you have a nugget of iron and are offering it for sale for 10.0 BTC, and I find an equivalent nugget of iron and offer it for sale for 5.0 BTC, and now nobody will pay you 10.0 BTC for your nugget, but will only pay you 5.0 BTC, I haven't "stolen" anything from you, even though you have suffered a loss of value.
Just because somebody's actions result in a loss of value for your assets, that does not mean anybody has "stolen" anything. Every day, people outcompete other people and the value of specific assets decline. That is not stealing. If I buy a bunch of stuff at certain times and sell a bunch of stuff at certain times, and it affects the market value of your stuff, that doesn't mean I'm a thief!