@tanguatlay,
Sozobe, in giving you that advice, Ms Tan, is following the "rule". This means that it is a prescription. Most US students are taught a lot of these prescriptions and they are not accurate representations of how English is used, or even how it has ever been used.
Quote:What makes the backshifting rule even more difficult is that there are exceptions in use - a fact to which most descriptive and ESL/EFL grammar books are sensitive, and one which calls the "rule" into question. ...
State-event remains true. Thompson (1994:109ff), drawing on a corpus database, suggests that present tense is retained in reported clauses when the author wishes to emphasize that the state or event in question holds true at the time of reporting and/or is not presented as something temporary.
The Grammar Book - An ESL/EFL Teacher's Course Celce-Murcia & Larsen-Freeman 2nd edition; page 690
There are other reasons for maintaining the present tense but this is adequate for this instance.