More importantly, since Avengers: Infinity War was shooting in the first half of 2017, months before this Disney and Fox deal was even announced, the Infinity War creative team would’s have had access to the Silver Surfer.
Now, Disney has announced that it plans on buying 21st Century Fox, and if the deal is finalized, that would mean that Silver Surfer would be among the numerous Marvel Comics who could finally be incorporated into the MCU.
Like the X-Men and Fantastic Four, Silver Surfer currently rests at 20th Century Fox, hence why he hasn’t appeared in the MCU at any point over the last 10 years.
There’s a chance that Marvel and Fox were able to work out a deal for the former company to use the Silver Surfer, similar to the Spider-Man deal arranged between Marvel and Sony, but one would imagine that something like that would have been publicly announced, if not at least rumored.