Unwell feral pigeon quarantine

[Johannes1]

I just rescued my third feral pigeon just picked the poor thing out of the gutter all puffed up, wobbly and breast bone sticking out.
Head said leave it as I can’t risk infecting my show birds but heart said it’s a life so worth saving.
It’s in isolation and medicated, feeding and drinking and faeces look normal now. Lethargic
Slight head shaking so I suspect maybe a nervous issue which I understand is likely not recoverable.
Is this bird likely to continue to be a threat to my birds?
Thanks everyone in anticipation.

[AdamArcher]

The head shaking would have me worried about PMV, which can be extremely deadly to your other birds.