[gbacon]

Case law agrees with your reading only in part, namely that the pardon power may be exercised at any time after its commission, that is, not preemptive as in being granted before the act being pardoned has taken place.

However, the broader context reads

The power of pardon conferred by the Constitution upon the President is unlimited except in cases of impeachment. It extends to every offence known to the law, and may be exercised at any time after its commission, either before legal proceedings are taken or during their pendency, or after conviction and judgment. The power is not subject to legislative control.

Ex parte Garland, 371 U.S. 333, 380 (1866) https://tile.loc.gov/storage-services/service/ll/usrep/usrep...

Changing it would require not a mere legislative act but a constitutional amendment.

To the executive alone is intrusted the power of pardon; and it is granted without limit.

United States v. Klein, 80 U.S. 128, 147 (1871) https://tile.loc.gov/storage-services/service/ll/usrep/usrep...