There's a requirement to name a senior manager: https://www.legislation.gov.uk/ukpga/2023/50/section/103
There's personal liability attached to being the named senior manager: https://www.legislation.gov.uk/ukpga/2023/50/section/110
Other nearby sections have additional personal liabilities. Like Sec 109 (5) (a) probably criminalizes your exact suggested response of walking away from Ofcom's inquiries: https://www.legislation.gov.uk/ukpga/2023/50/section/109 It depends on the legal definition of "permits the suppression of... any information required". We'd have to hire a UK lawyer for a confident answer.
All this is a couple sentences in the law. The law is 250 pages long. Ofcom's guidance was rounding 3,000 pages the last time I counted.
If you want to understand the OSA, I think the most accessible and valid writing available is by Neil Brown: https://onlinesafetyact.co.uk/ There's a lot developing as Ofcom continues to publish new rules and ignore questions, so I suggest reading the 'Replies' tab of his fediverse account.