[Cryptography] Why prefer symmetric crypto over public key crypto?

[Jaap-Henk Hoepman]

In this oped in the Guardian

http://www.theguardian.com/world/2013/sep/05/nsa-how-to-remain-secure-surveillance

Bruce Schneier writes: "Prefer symmetric cryptography over public-key cryptography." The only reason I can think of is that for public key crypto you typically use an American (and thus subverted) CA to get the recipients public key. 

What other reasons could there be for this advice?

Best,
Jaap-Henk

(I apologise for typos and being terse; this mail was written on an iPad)

--
Jaap-Henk Hoepman
TNO, Groningen & 
Dept. of Computer Science 
Radboud University Nijmegen 
(m) jhh at cs.ru.nl 
(w) www.cs.ru.nl/~jhh
(m) jaap-henk.hoepman at tno.nl
(t) +31 6 20619554
(t) @xotoxot
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