Why was this transaction relayed by nodes as a standard tx?
Because it only uses standard input and output types, that's why! Note that sending to (but not spending from) any not-yet-defined SegWit output type is standard.
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Isn't it non-standard to use uncompressed keys in inputs?
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Only in SegWit, they're standard in legacy scripts. There also exist "hybrid keys" that are non-standard everywhere.
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