DH and I took the DC and DH's parents out for lunch today. MIL has limited mobility and uses a wheelchair when out and about. Unfortunately, the cafe we ate at didn't have space for a wheelchair at the table so we helped MIL onto the bench and put the wheelchair in the corner. When we finished, DH and I went to the counter to pay while FIL helped MIL into the wheelchair. The DC sat there and didn't help, which is what we've always told them to do (they're 14 & 12 so probably could help but we don't want to risk injuring MIL any more). A man at the next table came over and started lecturing the DC about helping their nan! FIL made it very clear that he didn't want help, but the man wouldn't stop talking about how they were being disrespectful and lazy. Whilst he was saying this, he decided he was going to help instead! MIL was distressed by this as she doesn't like being touched by people she doesn't trust. AIBU to think this man was out of order for getting angry at 2 teenagers and attempting to "help" an elderly woman after being told he wasn't wanted multiple times?