The OS/2 Museum site has now moved to a completely different hosting setup (a VPS). There could well be various quirks caused by the move, although for the most part moving the WordPress setup went surprisingly (for me at least) smoothly.
The OS/2 Museum lasted 9 years on shared hosting. But it was no longer adequate, simply because at times the levels of legitimate traffic (to say nothing of spammers, bots, and other nuisances) were too high with no sensible way to control them.
We’ll see how long the new approach will last before something breaks again. Fingers crossed.