I think Daykin makes a really good point, in all honesty.
Yes, a gift that is very girly, bought for such a young child, can be problematic, especially in our current society. But I honestly don't think the answer is to claim that that anything pink, glittery, or girly is inherently bad. There is an equally dangerous train of thought there, because firstly, some people like that stuff (Heck, my 5yo DS loves playing with his sister's bangles and bracelets, enough that I bought him a couple of his own), and secondly, no child growing up today will reach adulthood without being aware that pink is used to symbolise girls, and blue to symbolise boys.
It doesn't matter if they like pink/blue, or even if they disagree with it. They will know it exists, because it still does. And they will still grow up hearing all those negative messages about femininity, about being female. We can't shelter children forever. And for a girl to grow up hearing that message, and then hearing that girly/pink things are bad, are rubbish, are tat, are things that girls maybe shouldn't play with... What are they supposed to feel?
Children don't see anything other than black and white. Something is "good" or it is "bad". "Okay, but a little problematic at times" doesn't arrive until much later. So we need to tread very carefully with our children, boys and girls, so that they don't fall into the trap of thinking that it's wrong to want to like pink things. There is nothing wrong with liking pink, with liking dolls, with wanting to be a princess when you play, as long as you accept and understand that it is just one of many options open to you. I don't see how branding pink/"girly" things as rubbish, or as something children shouldn't have can do anything other than harm those children who like them.
By all means, don't go out of your way to fill a girl's life with pink. Let her see other stuff too, encourage her to have a diverse range of interests and likes. But I don't think it's right to cordon off an entire colour as "not for you", because it presents a mixed message which could upset any girl further down the line.
I understand that the age of your child comes into question a little, but in all honesty, I can see a desk eventually being used for many things, few of which are the intended one. As a girl, I had dolls prams which I used to pretend were cargo vessels or ships, in which my dolls would ride out a flood before recolonising the devastated landscape. Large items of toy furniture can be a great springboard for the imagination. Perhaps look for the positives in this gift, and maybe talk to your MIL about age-appropriateness, and how you would like to foster a wide array of interests in your daughter, or next time, pre-empt the problem by offering some suggestions before the presents are bought. I give ideas to my parents and grandparents, with the reasoning that it avoids duplicates, but it also allows me to steer the present-buying in a direction I like.