This link shows that Bush did indeed sign this law.
New Statutory Rules for Witnessing Advance Directives in Texas
By S. Van McCrary, Health Law and Policy Institute
On June 18, 1999, Governor George W. Bush signed Texas Senate Bill 1260 into law. This bill consolidates all the previous Texas statutes related to advance directives--including the Natural Death Act, Durable Power of Attorney for Health Care, and Out-of-Hospital DNR Orders--into a unified statutory form.
http://www.law.uh.edu/healthlawperspectives/Death/990706New.htmlThis link has the actual Advance Directives Act which Bush signed.
Here's the part that says you have 10 days after a medical doctor and a review board decided you're terminal to find a facility willing to continue life support at your own expense. If you're familiar with the case mentioned in to OP you'll notice how hospitals don't jump at taking on these cases for free. When you fail to find a hospital to take your loved one they pull the plug.
(e) If the patient or the person responsible for the health
care decisions of the patient is requesting life-sustaining
treatment that the attending physician has decided and the review
process has affirmed is inappropriate treatment, the patient shall
be given available life-sustaining treatment pending transfer
under Subsection (d). The patient is responsible for any costs
incurred in transferring the patient to another facility. The
physician and the health care facility are not obligated to provide
life-sustaining treatment after the 10th day after the written
decision required under Subsection (b) is provided to the patient
or the person responsible for the health care decisions of the
patient unless ordered to do so under Subsection (g).
(e-1) If during a previous admission to a facility a
patient's attending physician and the review process under
Subsection (b) have determined that life-sustaining treatment is
inappropriate, and the patient is readmitted to the same facility
within six months from the date of the decision reached during the
review process conducted upon the previous admission, Subsections
(b) through (e) need not be followed if the patient's attending
physician and a consulting physician who is a member of the ethics
or medical committee of the facility document on the patient's
readmission that the patient's condition either has not improved or
has deteriorated since the review process was conducted.
(f) Life-sustaining treatment under this section may not be
entered in the patient's medical record as medically unnecessary
treatment until the time period provided under Subsection (e) has
expired.
This section shows how the law Bush signed gave the spouse legal rights over the parents if the person is unable to communicate.
§ 166.039. PROCEDURE WHEN PERSON HAS NOT EXECUTED OR
ISSUED A DIRECTIVE AND IS INCOMPETENT OR INCAPABLE OF
COMMUNICATION. (a) If an adult qualified patient has not
executed or issued a directive and is incompetent or otherwise
mentally or physically incapable of communication, the attending
physician and the patient's legal guardian or an agent under a
medical power of attorney may make a treatment decision that may
include a decision to withhold or withdraw life-sustaining
treatment from the patient.
(b) If the patient does not have a legal guardian or an agent
under a medical power of attorney, the attending physician and one
person, if available, from one of the following categories, in the
following priority, may make a treatment decision that may include
a decision to withhold or withdraw life-sustaining treatment:
(1) the patient's spouse;
(2) the patient's reasonably available adult children;
(3) the patient's parents; or
(4) the patient's nearest living relative.
http://www.capitol.state.tx.us/statutes/docs/HS/content/htm/hs.002.00.000166.00.htm