DollarsAndSense Answers:
Short answer: It depends.
Protection For Retirement Age
Based on the MOM website, the retirement age only applies if you join your employer before the age of 55.
Source: MOM
That means overseas Singaporeans who return home and join a company before the age of 55 will enjoy the retirement age protection.
Protection For Re-Employment
Aside from being medically fit and having satisfactory work performance, an individual will be eligible for re-employment after turning 62 if they have worked with their current employer for more than 3 years.
Source: MOM
This does not mean your existing employer cannot offer you a re-employment contract if you do not meet the eligibility criteria. They can if they want to, but remember, they are not obliged to do so.
Applies Equally To All Singaporeans & Permanent Residents (PRs)
For all Singaporeans and PRs, both the retirement and re-employment age will apply to you as long as you qualify for them based on the criteria stated above. Whether or not your work experience was from overseas does not matter in this case.