Yes, it could need N. However, it looks like a cultivar may have been grafted onto a Rhododendron ponticum seedling and died, leaving sprouts from the rootstock to carry on. Whatever the case may be, I would discard it myself as it consists of a stump with some badly yellowed R. ponticum sprouts - nothing I would want to have. And I would be concerned about it having a root rot or honey fungus problem that might spread to other plants later, should the opportunity arise.

It definitely needs nitrogen. It looks like it has poor drainage, needs mulch badly, and could use come fertilizer. It looks gangly like a plant that has been in the shade. Was this plant moved her from a shady area? It has lots of buds. See if you like it when it blooms. If you do, you may want to move it into a raised bed with good soil and mulch it.

Here is a link that might be useful: How to grow rhododendrons and azaleas.

Thank you both for your information! Here's a bit of backstory: The people who used to own the house put weed-suppressing fabric down almost everywhere. We found that this plant, another rhody, and an azalea where covered in this stuff right up to their necks, even though they're at a far-end of a lawn area (lots of sun). Of course grass and weeds were growing on top of it anyway. The "soil" underneath was actually gray! And it was pretty clayey (while elsewhere, the soil wasn't so sticky). We ripped the fabric up and I added some topsoil I had purchased for raised beds. That was in September, I think.
So today I took out more weeds and grass, put in some blood meal and covered the area around the plant with compost. I'm willing to wait and see what the blooms are like and what the N does before taking it out. Because nothing else is really around it, I'm not so worried about infecting other plants just yet.

Once again, thanks so much for your help!

Lawn also looks like it may be N deficient and perhaps also soggy in places. If it is a damp clay-like soil that becomes wet and remains so for long periods neither the lawn nor the rhododendron will be completely happy without the drainage being improved.