I have to agree that the climb "to" or descend "to" should NEVER be used by ATC or pilots. I make a point of never using it but ATC HK does on a regular basis .
I have struggled over the past 35 years in ATC wondering what ambiguity certain people find in the use of the word "to" in this context.
IF you consider it good airmanship to conform to Internationally agreed standard phraseology (yes, the U.S. is a signatory to ICAO as well in the context of the example below) when at all possible and
IF you understand that ICAO Doc 4444 standard phraseology is explicitly stated as;
CLIMB
TO (level), and
DESCEND
TO (level) [my bolding]
then you cannot possibly be confused that a perfectly executed instruction
"Connie 123, climb to niner thousand feet"
could possibly be construed as
"Climb twenty nine thousand feet Connie 123".
I'll be blunt. The guy is a moron. Anyone who thinks he has a case is also a moron.
Edit:
BTW, the FAA standard phraseology is also
CLIMB TO (level), and
DESCEND TO (level)
The fact that so many people have bastardized it over the years doesn't make the use of "TO" wrong.