The fiscal sponsor must be a 501(c)(3) organization as recognized by the IRS. The fiscal sponsor cannot be an organization whose tax-exempt status is pending. The sponsored project must be able to qualify for exemption under section 501(c)(3), even if the project has no intention of ever applying for it.
Pressing the Ignore button on the listed invitation on the LinkedIn site is effectively a soft rejection. The message then moves to your Archived folder. You can later choose to open the message again and accept the request.
When you post a bond for someone it is your responsibility to see that they make all required court appearances. If the person you posted the bond for fails to appear on any court date, the bond will be forfeited and you will lose your money.