In his answer to the question Dr. Monzer Kahf, Scholar in Islamic Economics & Financial Expert, who stated,

Technically he can (i.e. go for Hajj), unless this man has no other resource to pay for these loans, and the lenders, then they can take a legal action to restrict his disposition of his assets.

From a moral point, he is definitely wrong to go for Hajj before paying his debts, especially if he knows that creditors expect him to pay them as soon as possible.