I have a second hand Snoo basinett and I am considering purchasing the mosqitoe net from their website to help keep my cat away from the baby while he sleeps. Are mosquito nets safe?

Some concern has been expressed about safety when using mosquito nets/canopies
The main concern about the use of mosquito nets is the risk of baby pulling it down & become entangled in the netting.

Some cats have been known to jump into the bassinet or cot to be close to baby. This may risk baby’s head & face being covered.

Maybe it might be helpful to chat with a vet about how to manage a cat (or dog) with a new baby, & your concern of having cat access to baby’s cot/bassinet.
I also know that some people have installed a screen door on a baby’s bedroom to reduce the risk of a cat having access to baby’ in the cot or bassinet.

As far as bassinets (including SNOO) are concerned it is important to know that there are no Mandatory Standards for bassinets in Australia, however, Product Safety Australia does have some “buying tips” for bassinets.
https://www.productsafety.gov.au/products/babies-kids/kids-furniture/bassinettes

Red Nose has comprehensive information about bassinet use in general & using second hand products for baby’s sleep.
https://rednose.org.au/article/bassinets
Download Bassinets

https://rednose.org.au/article/second-hand-nursery-furniture

While we are not aware of any specific incidents with the SNOO product, the potential for the baby being “rocked” into a side/tummy position remains, particularly if restraints are not used, or used loosely.
The have been claims that the SNOO is the safest, most effective baby bed.

Red Nose (& other International Safe Sleep specialists) states that the safest place for baby to sleep is in a cot that meets mandatory standards.
The other concern about these types of products is the use of restraints or sleep positioners.
Red Nose does not recommend positional products such as anti-roll devices and items that fasten a baby into a sleeping position.
Products that restrict the movement of a baby or a baby’s head should not be used.
This is because there are no Australian Standards for these products and case studies have shown that these products can be unsafe.
There is strong scientific evidence to show that the best way to reduce the risk of SIDS and sleep accidents is to sleep babies on their back with face and head uncovered, to avoid exposing babies to tobacco smoke and to provide a safe sleeping environment.
https://rednose.org.au/article/is-it-safe-to-use-products-designed-to-keep-baby-in-a-particular-position

Red Nose also has the following information when buying products for baby’s sleep.
It is important for parents when they are thinking of buying a product for their baby to be able to make the best informed decision based on evidence of product safety. This is crucial for preventing SUDI or other fatal sleeping accidents.
https://rednose.org.au/article/baby-safe-sleeping-products