He's not, IMHO. Those strings attach to the funds in the new bill, not funds previously appropriated for other purposes. The President has Constitutional authority to act either through emergency or by law to secure the border against invasion and drug trafficking.
PLease see my comments here, actually someone smarter than me’s comments. :-):
No doubt about it; but he is talking about winning a court challenge - and securing the border may well involve him breaking the laws he just signed: building the fence where the law says he cannot, for example.
If you are going to argue to the court that the mind of the Congress is clear regarding the intent of the 'national emergency' statutes, then the court may decide that the mind of the Congress is clear in this budget bill since it passed both houses AND was signed by the President.
That is all that I am suggesting. (POTUS was sandbagged by the Congress) We will see.