A lot of those probably aren't advocating subjective idealism. Kantian views ('transcendental idealism'), Platonistic views ('platonic idealism'), Russellian views ('phenomenalism'), and Hegelian views ('objective idealism') are frequently called 'idealism' too. In the early 20th century, 'idealism' sometimes degraded to such an extent that it seemed to mean little more than the declaration 'I hate scientism and I think minds are interesting and weird'.

It's also worth noting that Peter probably had analytic philosophy in mind when he said 'Anglophone'. Most of the idealists in the survey are probably in the continental or historically Kantian tradition.