- While it's true Blofeld recovered from his injuries in On Her Majesty's Secret Service, his last appearance until this movie was in Diamonds Are Forever where we see him getting thrown around in a miniature submarine. The film makers might have figured a combination of that and the fact he likely only has access to mob doctors resulted in him ending up partially paralyzed once.
The Villa where Gonzales was relaxing at wasn't actually his property, but a mob-owned resort
There seemed to be a lot of people around as either hired security or "entertainment" for one hitman. That's not cheap nor sustainable no matter how well paid he was. More likely, it was a resort for high profile criminals and Gonzales was one of their guests which also served as a safe meeting point to be paid.Given the impunity shown by the guards that chase Bond and Melina, the multiple buildings and security, the location being a mob-owned business for hitmen and other high-profile criminals like The Continental in the John Wick series makes a lot more sense. After all, Gonzales was already dead, chasing them just to avenge their already dead employer served no real purpose, but it does if it was to maintain their reputation as a safe place for their clientele.
Alternately: Gonzales is a really popular, personable guy
Bond and Melina just happened to pay a visit when he was throwing a pool party for all his friends.
The Spy Who Loved Me was a factor in more than one way for Gogol
It's not just that they'd met as the main page notes, but also that the events of the movie had shown that Bond is not only a highly capable agent, he is a highly capable agent willing and proficient at working together with the Soviets when a common threat appears — quite a useful thing to have around in a world that has had organizations like SPECTRE and megalomaniacs like Stromberg and Drax!