Exporting the seed from Trust Wallet and importing it it into Blue Wallet or anywhere else doesn't make that seed more secure because it got created by a wallet you don't trust.
What an ironic way to put things.
.Regardless, the open source core of Trust Wallet should be safe to use, because anybody can audit the code, and it certanly doesn't look like there are any back[trap]doors or anything risky coming from Binance's side.