Having not used the tamron at rugby I couldn't say for sure, it's acceptable for powerboat, Sunday league football and cricket.
The guy was asking with a budget, it's within his budget and he'll get some great snaps. Like the poster above, I've managed in winter months with 1/500 on ISO100, not the best light but decent results. I wouldn't have told him to go spend a grand on glass before deciding he didn't really like taking photos.