Rubbish, I've done quite a few cross bleed starts on our A330's in the last 5 years and always done it during push without needing to increase thrust. The duct pressure always stayed above the required 25 psi with the start valve open. Naturally we read and do the procedure straight from the book.
In fact the A330 FCOM Supplementary Procedures Power Plant section procedure clearly states:--
"The remaining Engine is now started by crossbleed air from the operating Engine. This may be done during pushback...."
Now if yours doesn't say that then..............
I should add that we have RR Trent Engines...