I'm not sure that he was a fan when he bought into Saracens, but he became one very quickly.
One of the comments he made very early in his time there is that he pointed out that rugby supporters were creatures of habit, and as such they wanted to know that they had a home match every two weeks, so they could work to a pattern. He couldn't understand why the RFU made clubs play a couple of home matches, then a couple of away matches etc., thus acting as a deterrent to regular watching. His comments obviously worked, because that's what does happen now (for the most part at least).
He's also got an enormous memorabilia collection with lots of rare things in it. Friends of mine have seen it, and they're very complimentary about it. I (and they) realise that he's got them money to buy things, but they're displayed properly. Some of it is on display at Saracens, so it's on my list of things to do!