He has a point
LINX's fees are public and fixed, which I suspect is one part of his annoyance, since unlike other IXP's there is no scope for negotiation as with a profit making company:-
https://www.linx.net/products-services/service-fees-1
His solution, which is clearly got some self-interest, is that they could reduce their costs by utilising lower cost hardware like Arista. The current Extreme LAN will likely migrate to Arista over the next year, but the primary Juniper LAN is liable to stay where it is, hardware wise, not least since it's a massive emulated ring that uses VPLS.
Targets that *could* deliver some savings would be exchanges that LINX runs outside of London and Manchester: Edinburgh has never taken off, and LINX NOVA in Virginia seems a bit pointless in retrospect. Bear in mind the capex for all but the latter is very small since they mostly used equipment salvaged from the old London Foundry LAN, but the OPEX is there for the taking. However, it's really small change in the budget as a whole: the main cost is Juniper hardware.
LINX does act as a clearing house for the UK internet industry, but these costs are mainly covered by the sponsorship of meetings by vendors. Those expensive restaurant dinners are being covered out of other company sales budgets :-)