Isnt Metamask a Hot wallet is it really safe to store USDT ? if thats the case i may consider split my USDT between Metamask and Trezor
No it's not safe at all, you are not making anything better with that splitting plan, and it's not a good idea to hold USDT or any other stablecoins long term in any wallet.
There is nothing wrong with your trezor, just use it and there is no need for you to invent the wheel all overt again.