It appears that 1199SEIU Healthcare does not cover bariatric surgery. However, SEIU has regional plans that may have policies that vary. Some SEIU plans do offer bariatric surgery coverage. It is always recommended you call your insurance provider and ask to confirm your coverage for bariatric surgery.
These two resources indicate that 1199SEIU Healthcare does not offer any sort of coverage for weight loss surgery.
You can visit the 1199SEIU Healthcare site directly here.