As long as the distro has enough manpower to ensure that outdated packages are not a security risk. I run Debian stable because I don't mind old versions, and I trust the Debian people to keep my system reasonably secure.
It came with this one installed, and I'm gonna let it stay for the time being.
Also, the installed browsers are already a bit on the slow side, and I can imagine they would only get slower if I upgraded them.
I verify this in the Network Monitor pane.
Otherwise, I do not consider them trustworthy.