Isn't this the point here, what constitutes gross misconduct? Bringing the company into disrepute is the obvious one but at tribunal this could be argued, no way am I saying it's not offensive, it 100% is, but to who? Lets speculate that the company doesn't have a clause in their contracts in relation to activities outside work, if the company is as flaky as some suggest then HR corners could have been cut, I had a situation where one of my staff openly criticised company policy and the CEO by way of a comment in a local paper, this is a large utility company supplying millions of people with water and a fully functioning HR department, suspension was immediate pending an enquiry in relation to gross misconduct, I lost due to no mention of bringing the company into disrepute in his contract.
In this case it would be preferable that this cretin just fades away into obscurity.